Wear out soldier, returning insect (6)
I believe the answer is:
earwig
'insect' is the definition.
(I know that earwig is a type of insect)
'wear out soldier returning' is the wordplay.
'out' is an anagram indicator (out can mean wrong or inaccurate).
'soldier' becomes 'GI' (GI can mean a US soldier).
'returning' says the letters should be written in reverse.
'gi' written backwards gives 'ig'.
'wear' is an anagram of 'earw'.
'earw'+'ig'='EARWIG'
(Other definitions for earwig that I've seen before include "court" , "Creepy type" , "Small insect with pincers at end of its body" , "Close acquaintance" , "listen in?" .)