Reward from bishop -- our treat (5)
I believe the answer is:
bonus
'reward' is the definition.
(I've seen this before)
'bishop our treat' is the wordplay.
'bishop' becomes 'B' (abbreviation used in chess).
'our treat' becomes 'on us' (something 'on us' or 'our treat' is paid for by us).
'b'+'onus'='BONUS'
'from' is the link.
(Other definitions for bonus that I've seen before include "The advantage" , "Payment additional to the expected or usual" , "Additional incentive payment" , "Perk" , "Extra payment - reward" .)