A student getting small grant (5)
I believe the answer is:
allow
'grant' is the definition.
('allow' can be a synonym of 'grant')
'a student getting small' is the wordplay.
'student' becomes 'l' (as in L-plates for learner drivers).
'getting' is a charade indicator (letters next to each other).
'small' becomes 'low' ('low' can be a synonym of 'small'**).
'a'+'l'+'low'='ALLOW'
(Other definitions for allow that I've seen before include "praise no more" , "Permit or acknowledge" , "OK" , "Acknowledge - concede" , "Permit, let happen" .)