After restraint certain to get cover again (8)
I believe the answer is:
reinsure
'cover again' is the definition.
('insure' can be a synonym for 'cover' so perhaps 'reinsure' is OK for 'cover again')
'after restraint certain' is the wordplay.
'after' says to put letters next to each other.
'restraint' becomes 'rein' (I've seen this before).
'certain' becomes 'sure' (synonyms).
'rein' next to 'sure' is 'REINSURE'.
'to get' is the link.
(Other definitions for reinsure that I've seen before include "Take out another policy" , "recover?" , "Cover again" , "Pass on a risk of having to pay compensation" .)