Farron and Henman face off over priest setting deadline (4,5)
I believe the answer is:
time limit
'deadline' is the definition.
(I've seen this before)
'farron and henman face off over' is the wordplay.
'farron' becomes 'tim' (Tim Farron).
'and' means one lot of letters go next to another.
'henman' becomes 'tim' (Tim Henman).
'face off' becomes 'ile' (I can't explain this - if you can you should give a lot more credence to this answer).
'over' shows that the letters should be reversed in order.
'tim'+'ile'='timile'
'timile' back-to-front is 'elimit'.
'tim'+'elimit'='TIME-LIMIT'
'priest setting' is the link.
This may not be right. Some or all of it may be part of another bit of the clue.
(Other definitions for time limit that I've seen before include "Deadline" , "Point before which something must be achieved" , "maximum duration" , "within which task must be done" , "Prescribed term" .)