Loose, sleeveless garment (5)
I believe the answer is:
tunic
'loose sleeveless garment' is the definition.
(I've seen this before)
This is the entire clue.
(Other definitions for tunic that I've seen before include "Dress for soldier" , "Jacket of some soldiers" , "Partly uniform" , "Short uniform coat" , "Loose fitting light cloak extending to the hip or lower" .)