Cover found in gamekeeper's heather (7)
I believe the answer is:
sheathe
'cover' is the definition.
(sheathing is a kind of covering)
'in gamekeeper's heather' is the wordplay.
'in' indicates a hidden word.
'SHEATHE' is hidden within 'gamekeepers heather'.
'found' acts as a link.
(Other definitions for sheathe that I've seen before include "Put (a sword) into its holder" , "Put (a sword) it its cover" , "Encase in protection" , "Put into scabbard" , "Protective cover, for sword say" .)