Soldiers returned with new evidence (4)
I believe the answer is:
sign
'evidence' is the definition.
(sign is a kind of evidence)
'soldiers returned with new' is the wordplay.
'soldiers' becomes 'gis' (I've seen this in other clues).
'returned' shows that the letters should be reversed in order.
'with' says to put letters next to each other.
'new' becomes 'n' (common abbreviation eg NT for New Testament).
'gis' written backwards gives 'sig'.
'sig'+'n'='SIGN'
(Other definitions for sign that I've seen before include "Manifestation" , "Indicator" , "Omen or indication" , "Public display of a message" , "Show" .)