Lawman may be fresh if in trouble (7)
I believe the answer is:
sheriff
'lawman' is the definition.
(sheriff is a kind of lawman)
'fresh if in trouble' is the wordplay.
'in trouble' is an anagram indicator.
'fresh'+'if'='freshif'
'freshif' is an anagram of 'SHERIFF'.
'may be' is the link.
(Other definitions for sheriff that I've seen before include "Scots judge" , "US law enforcement officer" , "US county law enforcer" , "American lawman" , "court officer" .)