Cricketer leaving middle a hero (6)
I believe the answer is:
batman
'a hero' is the definition.
(I've seen this before)
'cricketer leaving middle' is the wordplay.
'cricketer' becomes 'batsman' (batsman is a type of cricketer).
'leaving middle' suggests removing the centre.
'batsman' with its middle removed is 'BATMAN'.
(Other definitions for batman that I've seen before include "Army servant - comic character" , "Comic book hero with Robin as a sidekick" , "He helps the officer" , "gives help to one in a mess?" , "valet" .)