Bishop and I agree to provide extras (4)
I believe the answer is:
byes
'extras' is the definition.
(I've seen this before)
'bishop and i agree' is the wordplay.
'bishop' becomes 'B' (chess abbreviation).
'and' means one lot of letters go next to another.
'i agree' becomes 'yes' (both are affirmative answers).
'b'+'yes'='BYES'
'to provide' is the link.
(Other definitions for byes that I've seen before include "Cricket extras" , "Scores" , "In cricket, runs scored from balls that pass the batman without being hit" , "Runs not from bat" , "Extra runs" .)