Retribution in Geneva recollected once, with nothing omitted (9)
I believe the answer is:
vengeance
'retribution' is the definition.
(synonyms)
'geneva recollected once with nothing omitted' is the wordplay.
'recollected' is an anagram indicator.
'with nothing' becomes 'o' (I've seen this in other clues).
'omitted' is a deletion indicator.
'once' with 'o' taken away is 'nce'.
'geneva' anagrammed gives 'vengea'.
'vengea'+'nce'='VENGEANCE'
'in' is the link.
(Other definitions for vengeance that I've seen before include "Retributory punishment" , "Retribution" .)