Fit one rep with a return canapé (8)
I believe the answer is:
aperitif
'canape' is the definition.
(thesaurus)
'fit one rep with a return' is the wordplay.
'one' becomes 'i' (Roman numeral).
'with' says to put letters next to each other.
'return' is a reversal indicator.
'fit'+'i'+'rep'+'a'='fitirepa'
'fitirepa' written backwards gives 'APERITIF'.
(Other definitions for aperitif that I've seen before include "Alcoholic drink to whet the appetite" , "If pirate may have a drink before dinner?" , "Appetite stimulant drink" , "Pre-nosh tipple?" , "whistle-whetting drink" .)