Throw in a little salad dressing (3)
I believe the answer is:
add
'throw in' is the definition.
(I've seen this in another clue)
'a little salad dressing' is the wordplay.
'a little' indicates a hidden word (a little bit of the clue).
'ADD' is hidden within 'salad dressing'.
(Other definitions for add that I've seen before include "Put together (numbers)" , "Give more" , "Put together - attach" , "Contribute" , "Reason for difficulty learning" .)