Cover for sun coming out in anger (6)
I believe the answer is:
insure
'cover' is the definition.
('insure' can be a synonym of 'cover')
'sun coming out in anger' is the wordplay.
'coming out' is an anagram indicator.
'in' is an insertion indicator.
'anger' becomes 'ire' ('ire' can be a synonym of 'anger').
'sun' with letters rearranged gives 'nsu'.
'nsu' placed within 'ire' is 'INSURE'.
'for' acts as a link.
(Other definitions for insure that I've seen before include "Take out a policy" , "Take out cover" , "Protect against possible loss" , "Provide protection against risk or damage" , "Guarantee; make secure" .)