Meat cut for umpire in part (4)
I believe the answer is:
rump
'meat cut' is the definition.
(I know that rump is a type of cut of beef)
'for umpire in part' is the wordplay.
'in part' says the answer is hidden in the clue.
'RUMP' is hidden in the letters of 'for umpire'.
(Other definitions for rump that I've seen before include "Hind part; small remnant" , "Rear; buttocks" , "Bottom - cut of steak" , "Hind part of body" , "historical Parliament" .)