Student, one wearing short dress for a prank (6)
I believe the answer is:
frolic
'a prank' is the definition.
(thesaurus)
'student one wearing short dress' is the wordplay.
'student one' becomes 'li' (I am not sure about this - if you are sure you should believe this answer much more).
'wearing' is an insertion indicator.
'short' means to remove the last letter.
'dress' becomes 'frock' (frocking is a kind of dressing).
'frock' with its final letter taken off is 'froc'.
'li' going inside 'froc' is 'FROLIC'.
'for' is the link.
Can you help me to learn more?
(Other definitions for frolic that I've seen before include "Caper, cavort" , "Lively play, romp" , "Play about in lively cheerful way" , "'Frisk, gambol (6)'" , "fun" .)