Stipulated about gratuity (3)
I believe the answer is:
tip
'gratuity' is the definition.
(as in a gratuity to a waiter)
'stipulated about' is the wordplay.
'about' says the answer is hidden in the clue (the clue goes around or about the answer).
'TIP' can be found hidden inside 'stipulated'.
(Other definitions for tip that I've seen before include "Bonus" , "Point; hint" , "Hint or dumping ground" , "Warning" , "given gratuitously" .)