Stupid students swapping sides (5)
I believe the answer is:
crass
'stupid' is the definition.
(thesaurus)
I can't explain the remainder of the clue.
(Other definitions for crass that I've seen before include "Coarse" , "Totally lacking in sensibility" , "Witless" , "Grossly insensitive" , "'Gross, vulgar (5)'" .)