Pad Thai garnish (4)
I believe the answer is:
lime
'pad thai garnish' is the definition.
(I've seen this in another clue)
This is the entire clue.
(Other definitions for lime that I've seen before include "Another name for the linden tree" , "Having no money" , "Bright light green" , "Citrus fruit - shade of green" , "Citrus tree - non-citrus tree" .)