Second-hand medal going first at a loss (7)
I believe the answer is:
bemused
'at a loss' is the definition.
'second-hand medal going first' is the wordplay.
'second hand' becomes 'used' (I've seen this before).
'medal' becomes 'bem' (British Empire Medal).
'going first' is a charade indicator (letters next to each other).
'used' put after 'bem' is 'BEMUSED'.
(Other definitions for bemused that I've seen before include "Perplexed or absorbed in thought" , "Confused, bewildered" , "Puzzled" , "Dazed" , "Lost for words" .)