Coin found by soldier retreating from base (7)
I believe the answer is:
ignoble
'base' is the definition.
(both can mean dishonourable or shameful)
'coin found by soldier retreating' is the wordplay.
'coin' becomes 'noble' (I've seen this before).
'found by' says to put letters next to each other.
'soldier' becomes 'GI' (GI can mean a US soldier).
'retreating' is a reversal indicator.
'gi' written backwards gives 'ig'.
'noble' after 'ig' is 'IGNOBLE'.
'from' acts as a link.
(Other definitions for ignoble that I've seen before include "Contemptible" , "Not worthy in character or purpose" , "Cheap" , "Completely lacking in character or purpose" , "Inferior" .)