After capture, letters received (7)
I believe the answer is:
postbag
'letters received' is the definition.
(I've seen this before)
'after capture' is the wordplay.
'after' becomes 'post' (suffix meaning after, eg post-war).
'capture' becomes 'bag' (both can mean to secure or acquire).
'post'+'bag'='POSTBAG'
(Other definitions for postbag that I've seen before include "one's letters" , "What one receives collectively" , "All delivered" , "carrier for Royal Mail" , "Letters received" .)