Co-operate to meet delivery (4,4)
I believe the answer is:
play ball
'co-operate' is the definition.
(I've seen this before)
'meet delivery' is the wordplay.
'meet' becomes 'play' ('play' can be a synonym of 'meet'**).
'delivery' becomes 'ball' (ball is a kind of delivery).
'play'+'ball'='PLAY BALL'
'to' is the link.
(Other definitions for play ball that I've seen before include "Co-operate" , "go along" , "meet a delivery?" , "Be cooperative" , "Do what is needed" .)