Old soldier turning in torn decoration (8)
I believe the answer is:
ornament
'decoration' is the definition.
(I know that decoration can be written as ornament)
'old soldier turning in torn' is the wordplay.
'old' becomes 'o' (abbreviation as in OT - Old Testament).
'soldier' becomes 'man' (man can mean a soldier).
'turning' says the letters should be written in reverse.
'in' means one lot of letters goes inside another.
'torn' becomes 'rent' (synonyms).
'man' backwards is 'nam'.
'nam' going into 'rent' is 'rnament'.
'o'+'rnament'='ORNAMENT'
(Other definitions for ornament that I've seen before include "deck" , "small decorative object" , "accessory" , "A mark of honour" , "Decorative item" .)