Credit card finally found in marketplace on return (5)
I believe the answer is:
kudos
'credit' is the definition.
(I've seen this before)
'card finally found in marketplace on return' is the wordplay.
'finally' indicates one should take the final letters.
'found in' is an insertion indicator.
'marketplace' becomes 'souk' (souk is a kind of marketplace).
'on return' says the letters should be written backwards.
The final letter of 'card' is 'd'.
'd' inserted inside 'souk' is 'soduk'.
'soduk' backwards is 'KUDOS'.
(Other definitions for kudos that I've seen before include "Praise and honours" , "Laurels" , "Renown" , "Honour - cachet" , "'Credit, honour or prestige (5)'" .)