Smooth guy, gutted, accepts defeat (6)
I believe the answer is:
glossy
'smooth' is the definition.
('glossy' can be similar in meaning to 'smooth')
'guy gutted accepts defeat' is the wordplay.
'gutted' means to remove the middle letters (to gut something is to remove its insides).
'accepts' is an insertion indicator.
'defeat' becomes 'loss' (I've seen this before**).
'guy' with its centre taken out is 'gy'.
'gy' going around 'loss' is 'GLOSSY'.
(Other definitions for glossy that I've seen before include "Shiny on the surface" , "Shiny; type of magazine" , "Smooth and shining" , "Magazine printed on good quality paper" , "Smooth, shiny" .)