Two dry gallons (4)
I believe the answer is:
peck
'two dry gallons' is the definition.
(I've seen this in another clue)
This is all the clue.
(Other definitions for peck that I've seen before include "Attack with beak" , "Nibble" , "Country; letter I (radio communications)" , "Kiss; part of bushel" , "Kiss; old dry measure" .)