Small amount, whit (3)
I believe the answer is:
tad
I believe this clue is a double definition.
'small amount' is the first definition.
('a tad' is a small amount)
'whit' is the second definition.
(I've seen this in another clue)
(Other definitions for tad that I've seen before include "little boy" , "Little bit" , "(A) bit, touch" , "A small amount (colloq.)" , "Slight amount" .)