Finish with detectives only claiming victory (8)
I believe the answer is:
dissolve
'finish' is the definition.
(thesaurus)
'detectives only claiming victory' is the wordplay.
'detectives' becomes 'dis' (Detective Inspectors, DIs).
'only' becomes 'sole' ('sole' can be a synonym of 'only').
'claiming' means one lot of letters goes inside another.
'victory' becomes 'v'.
'sole' placed around 'v' is 'solve'.
'dis'+'solve'='DISSOLVE'
'with' acts as a link.
(Other definitions for dissolve that I've seen before include "Melt in fluid" , "Annul or end, a marriage say" , "Nullify" , "A smooth change from one film image to another" , "Disperse or melt in liquid" .)