Hindu ascetic greeting US soldier (4)
I believe the answer is:
yogi
'hindu ascetic' is the definition.
(I've seen this before)
'greeting us soldier' is the wordplay.
'greeting' becomes 'yo'.
'us soldier' becomes 'GI' (GI can mean an American soldier).
'yo'+'gi'='YOGI'
(Other definitions for yogi that I've seen before include "Cartoon bear; Hindu ascetic" , "Hindu mystic" , "master of posturing?" , "Someone practising certain Hindu disciplines" , "teacher of well-being" .)