Gather graduate stops fool (5)
I believe the answer is:
amass
'gather' is the definition.
('amass' can be a synonym of 'gather')
'graduate stops fool' is the wordplay.
'graduate' becomes 'ma' (abbreviation for Master of Arts).
'stops' means one lot of letters goes inside another.
'fool' becomes 'ass' (ass is a kind of fool).
'ma' put within 'ass' is 'AMASS'.
(Other definitions for amass that I've seen before include "Sodium chloride" , "Stock up on" , "Accrue, heap up" , "Gather together, pile up" , "store" .)