Modicum, iota (3)
I believe the answer is:
tad
I believe this clue is a double definition.
'modicum' is the first definition.
(I've seen this in another clue)
'iota' is the second definition.
(I've seen this in another clue)
(Other definitions for tad that I've seen before include "Small bit" , "Modest amount" , "Slight amount" , "(A) bit, touch" , "Smidgen" .)