Judge some apple tarts I gamely served up (10)
I believe the answer is:
magistrate
'judge' is the definition.
(I know that judge can be written as magistrate)
'some apple tarts i gamely served up' is the wordplay.
'some' indicates the answer is hidden within the clue (some of the parts of the word are used).
'served up' says the letters should be written in reverse (in a down clue, letters go up).
'etartsigam' is hidden in the letters of 'apple tarts i gamely'.
'etartsigam' reversed gives 'MAGISTRATE'.
(Other definitions for magistrate that I've seen before include "Person in court" , "Justice of the peace" , "Law enforcer" , "Court official" , "Court officer" .)