Large amount of cotton socks (4)
I believe the answer is:
tons
'large amount' is the definition.
(I've seen this in another clue)
'of cotton socks' is the wordplay.
'of' indicates the answer is hidden within the clue.
'TONS' is hidden within 'cotton socks'.
(Other definitions for tons that I've seen before include "Each is equivalent to 2240 pounds" , "A lot" , "Lots" , "Loads (sl.)" .)