Head off troubles and rest (6)
I believe the answer is:
others
'rest' is the definition.
(I've seen this before)
'head off troubles' is the wordplay.
'head off' means to remove the first letter.
'troubles' becomes 'bothers' ('bother' can be a synonym of 'trouble').
'bothers' with its first letter taken away is 'OTHERS'.
'and' is the link.
(Other definitions for others that I've seen before include "He rots (anag.)" , "Not these, alternatives" , "Not the same one already mentioned" , "Different ones" , "Different from those already mentioned" .)