Red trees unsettled runaway (8)
I believe the answer is:
deserter
'runaway' is the definition.
(I've seen this in another clue)
'red trees unsettled' is the wordplay.
'unsettled' indicates an anagram.
'red'+'trees'='redtrees'
'redtrees' with letters rearranged gives 'DESERTER'.
(Other definitions for deserter that I've seen before include "Military runaway" , "Serviceman running away" , "Illegal army leaver" , "One illegally leaving armed forces" , "military offender" .)