Turncoat held by soldiers gets free (6)
I believe the answer is:
gratis
'free' is the definition.
('gratis' can be a synonym of 'free')
'turncoat held by soldiers' is the wordplay.
'turncoat' becomes 'rat' (I've seen this in other clues).
'held by' means one lot of letters goes inside another.
'soldiers' becomes 'gis' (I've seen this in other clues).
'rat' inserted into 'gis' is 'GRATIS'.
'gets' acts as a link.
(Other definitions for gratis that I've seen before include "Costing nothing, free" , "Free, costs nothing" , "Free (Latin)" , "not charged" , "Without charge" .)