Whip on prof's rear and quickly show your bits (5)
I believe the answer is:
flash
'quickly show your bits' is the definition.
(as in flashing someone)
'whip on prof's rear' is the wordplay.
'whip' becomes 'lash' (synonyms).
'on' is a charade indicator (letters next to each other).
'rear' says to take the final letters (the back of the word).
The last letter of 'prof' is 'f'.
'lash' put after 'f' is 'FLASH'.
'and' acts as a link.
(Other definitions for flash that I've seen before include "sort of flooding" , "Twinkling" , "Ostentatious" , "Camera fitment" , "Momentary gleam of light" .)