Crazy graduates needing to take time (4)
I believe the answer is:
bats
'crazy' is the definition.
(I've seen this before)
'graduates needing to take time' is the wordplay.
'graduates' becomes 'bas' (people with Bachelor of Arts degrees).
'needing to take' is an insertion indicator.
'time' becomes 't' (abbreviation).
'bas' going around 't' is 'BATS'.
(Other definitions for bats that I've seen before include "Clubs; flying mammals" , "Bonkers (sl.)" , "Mad; mammals" , "out to lunch" , "Crazy - mammals" .)