Instrumentally, the stuff that happens at the end (a full band kind of thing) seems "out of the blue" and unnecessary. Better to stick with the things that have been playing through the rest of the song. The clarinet and piano are nice.

Lyrically, there are a number of places where you could drop little words to get better prosody.

Sax sings sweet, bass keeps thumpin'
the solo's never stop;
Groovin' beat is really sumpin'
They call it the Harlem Bop!

...
Dipped my toe in the groovin' jam
Laid my solo on the Harlem Bop.

...
Folks keep truckin', the band right with 'em,
everyone swingin' with the Harlem Bop.

All just ideas, since you asked.
It's a good start...