Possibly sent out East for years (5)
I believe the answer is:
teens
'for years' is the definition.
(I have seen 'Adolescent years' mean 'teens' so perhaps 'years' could also mean 'teens')
'possibly sent out east' is the wordplay.
'possibly' indicates anagramming the letters.
'out' means one lot of letters goes inside another.
'east' becomes 'e' (synonyms).
'sent' is an anagram of 'tens'.
'tens' enclosing 'e' is 'TEENS'.
(Other definitions for teens that I've seen before include "Years 13-19" , "13-19 age group" , "seven-year period" , "The years 13 to 19" , "Adolescence" .)