Devil of a stalemate in court (5)
I believe the answer is:
deuce
I believe this clue is a double definition.
'devil' is the first definition.
(euphemism for the devil, as in 'what the deuce')
'a stalemate in court' is the second definition.
(score of 40 all in tennis)
'of' is the link.
(Other definitions for deuce that I've seen before include "Two in cards - score in tennis" , "score at Wimbledon?" , "40 - 40 (tennis)" , "40-40 in tennis -- 2 in cards" , "Forty-all in tennis" .)