Student and new dean give aid (4,1,4)
I believe the answer is:
lend a hand
'aid' is the definition.
(I've seen this in another clue)
'student and new dean give' is the wordplay.
'student' becomes 'l' (as in L-plates for learner drivers).
'and' says to put letters next to each other.
'new' indicates anagramming the letters.
'give' becomes 'hand' (synonyms).
'dean' with letters rearranged gives 'enda'.
'l'+'enda'+'hand'='LEND A HAND'
(Other definitions for lend a hand that I've seen before include "To assist" , "Turn to and help" , "Provide help" , "temporarily transfer an employee" , "Give assistance" .)