Send on attacking player (7)
I believe the answer is:
forward
I believe this is a double definition.
'send on' is the first definition.
(as in forwarding a letter on)
'attacking player' is the second definition.
(eg in football)
(Other definitions for forward that I've seen before include "moving ahead" , "Attacking player" , "Footballer; ahead in time" , "Bold, overfamiliar" , "Officious" .)