A Japanese entertainer - she gets involved with a GI (6)
I believe the answer is:
geisha
'a japanese entertainer' is the definition.
(geishas traditionally hosted or entertained men)
'she gets involved with a gi' is the wordplay.
'gets involved with' indicates anagramming the letters.
'a'+'gi'='agi'
'she' with its letters mixed up with 'agi' gives 'GEISHA'.
(Other definitions for geisha that I've seen before include "girl from the orient" , "Japanese woman trained to please men" , "Japanese hostess who entertains men" , "A Japanese woman who entertains men" , "One employed to look after men" .)