Female entertainer his age? Possibly (6)
I believe the answer is:
geisha
'female entertainer' is the definition.
(I've seen this before)
'his age? possibly' is the wordplay.
'possibly' is an anagram indicator.
'his'+'age'='hisage'
'hisage' is an anagram of 'GEISHA'.
(Other definitions for geisha that I've seen before include "Japanese paid companion" , "Japanese hostess who entertains men" , "Japanese serving girl" , "Female escort" , "Entertainer in a kimono?" .)