Every movie has a few cliches. You’ve just got to finesse them.

In “Burlesque,” writer/director Steve Antin lays on the cliches with a trowel, delivering a show-biz tale packed with elements that were starting to smell iffy back in the Great Depression.

Iowa waitress Ali (Christina Aguilera) heads to LA with a dream of performing. She stumbles across a basement nightclub called Burlesque, is enraptured by the elaborate girly floor shows, gets a job serving drinks and, one special night, must step into the star’s shoes.

Stop me if this sounds familiar.

The problem with “Burlesque” is that it behaves as if these hoary elements were as fresh as morning dew. No post-modern twists. No ironic commentary on overworked tropes. No so-bad-it’s-good knuckleheadedness a la “Showgirls.”

In other words, no finesse. Just plot and dialogue that land with audible thuds.

Saving the film from disaster are Aguilera, a popular singer tackling her first big-screen leading role, and the musical numbers. Both allow us to forget, if only momentarily, how weary this could have become.

In the film’s first few minutes, Aguilera’s Ali knocks our socks off by belting out Etta James’ “Something’s Got a Hold on Me” while packing her suitcase for her escape to Lalaland. This woman has one of the great voices, and from that moment on we live in anticipation of the next time she’ll burst into song.

As an actress she more than holds her own. Not that Antin’s screenplay offers much of a challenge. Ali’s character arc goes from determined sweet young thing to really determined sweet young thing. But Aguilera sells it with a minimum of fuss while being very, very watchable.

Co-star Cher, playing the club’s tough-on-the-outside, soft-on-the-inside owner, Tess, rules this roost like a bawdy mother hen. Aside from overly puffy lips, the 64-year-old looks pretty good. Plus she has one big production number and a more modest vocal solo that should keep diva devotees sighing contentedly.

Other characters proffered by Antin also come right out of central casting: Kristen Bell as the ego-driven cabaret star deposed by Ali; Cam Gigandet as the friendly bartender (don’t be fooled by the eyeliner — he’s straight) who takes in our girl when her apartment is burgled (do we sense a romance developing?); Stanley Tucci as Burlesque’s gay director/stage manager (basically his “Devil Wears Prada” role repurposed); Eric Dane as a real estate magnate on the prowl to buy the financially strapped club and build a high-rise. Pretty much wasted are Peter Gallagher as Tess’ fretful ex and Alan Cumming as the club’s doorman.

The musical numbers — the real reason to spend any time with “Burlesque” — aren’t particularly original, but they’re fun. Though Aguilera gets to parody Sally Rand’s famous fan dance, these aren’t classic striptease numbers. More like riffs on “Cabaret”-style decadence with lots of ersatz Fosse pelvic thrusts and extended legs. Musical sources range from “Diamonds Are a Girl’s Best Friend” to ’60s go-go.

The Busby Berkeley-esqe joke is that these productions are a) so big and elaborate that there’s no way a little basement club could accommodate them and b) so expensive that Tess would require the income of a Vegas casino to underwrite them.

But, hey, if you’re looking for logic, “Burlesque” isn’t your movie to begin with.