Don overturned tennis umpire's call (3,2)
I believe the answer is:
not up
'tennis umpire's call' is the definition.
(tennis term)
'don overturned' is the wordplay.
'don' becomes 'put on' (synonyms).
'overturned' says the letters should be written backwards.
'puton' backwards is 'NOT UP'.
(Other definitions for not up that I've seen before include "with tennis call" , "still in bed" , "call in court" .)