A couple of flyers that striker uses when dispatching deliveries (7,3)
I believe the answer is:
cricket bat
'that striker uses when dispatching deliveries' is the definition.
(used when striking in cricket)
'a couple of flyers' is the wordplay.
'a couple of flyers' means two substitutions for 'flyer'.
'flyer' becomes 'cricket' (crickets can fly).
'flyer' becomes 'bat' (bats can fly).
'cricket'+'bat'='CRICKET BAT'
(Other definitions for cricket bat that I've seen before include "requirement for four or six, perhaps?" , "that's used in test" , "might be found in the pavilion" , "One used to glance" , "willow" .)