Onset of dark circles, mark for ruin (4)
I believe the answer is:
doom
'ruin' is the definition.
(I've seen this in another clue)
'onset of dark circles mark' is the wordplay.
'onset of' suggests taking the first letters.
'circles' becomes 'oo' (resembles two O's).
'mark' becomes 'm'.
The first letter of 'dark' is 'd'.
'd'+'oo'+'m'='DOOM'
'for' is the link.
(Other definitions for doom that I've seen before include "Bad destiny" , "Unfortunate fate" , "__ and gloom" , "Death, destruction" , "Judgement" .)