Finished and ruined, in conclusion (6)
I believe the answer is:
upshot
'conclusion' is the definition.
(I've seen this before)
'finished and ruined' is the wordplay.
'finished' becomes 'up' (eg 'time's up' means the time is finished).
'and' is a charade indicator (letters next to each other).
'ruined' becomes 'shot' (I've seen this in another clue).
'up'+'shot'='UPSHOT'
'in' is the link.
(Other definitions for upshot that I've seen before include "One killed the albatross" , "Outcome of vertical discharge?" , "issue" , "skier" , "anti-aircraft fire?" .)