Rewarded good service (6)
I believe the answer is:
tipped
'rewarded good service' is the definition.
(I've seen this in another clue)
This is all the clue.
(Other definitions for tipped that I've seen before include "Gave reward (to waiter)" , "Crowned" , "Predicted to be a winner" , "Given a gratuity" , "Gave gratuity to or touched" .)