Marksman getting small owl, perhaps (7)
I believe the answer is:
shooter
'marksman' is the definition.
(thesaurus)
'small owl perhaps' is the wordplay.
'small' becomes 's' (abbreviation - e.g. clothes size).
'owl perhaps' becomes 'hooter'.
's'+'hooter'='SHOOTER'
'getting' acts as a link.
(Other definitions for shooter that I've seen before include "One who has an attempt at goal" , "Hit man" , "Gun user" , "Gun (sl.)" , "One from Arsenal" .)