Sniper who lost control (9)
I believe the answer is:
ownership
'control' is the definition.
(ownership is a kind of control)
'sniper who lost' is the wordplay.
'lost' indicates anagramming the letters.
'sniper'+'who'='sniperwho'
'sniperwho' is an anagram of 'OWNERSHIP'.
(Other definitions for ownership that I've seen before include "Legal title" , "Proprietary right of possession" , "Proprietorship, possession" , "The right of possessing something" .)