Key batsman (6)
I believe the answer is:
opener
I believe this clue is a double definition.
'key' is the first definition.
(thesaurus)
'batsman' is the second definition.
(I've seen this before)
(Other definitions for opener that I've seen before include "introduction" , "In cricket, a batsman who plays the first ball of an innings" , "Corkscrew, for example" , "leading batsman" , "No.1 or No.2 bat" .)