Withdraw, carrying emptied rifle, being cowardly (8)
I believe the answer is:
recreant
'cowardly' is the definition.
(similar in meaning)
'withdraw carrying emptied rifle' is the wordplay.
'withdraw' becomes 'recant' (I've seen this before).
'carrying' means one lot of letters goes inside another.
'emptied' means to remove the middle letters.
'rifle' with its middle removed is 're'.
'recant' placed around 're' is 'RECREANT'.
'being' acts as a link.
(Other definitions for recreant that I've seen before include "yellow" , "disloyal" , "Cowardly; apostate" , "Craven, apostate" .)