100's too old for insurance (8)
I believe the answer is:
coverage
'insurance' is the definition.
('coverage' can be a synonym of 'insurance')
'100's too old' is the wordplay.
'100' becomes 'c' (roman numeral).
'too old' becomes 'overage' (I've seen this before).
'c'+'overage'='COVERAGE'
'for' is the link.
(Other definitions for coverage that I've seen before include "policy provision" , "Commentary" , "Treatment of news" , "insurance" , "Press reporting" .)