Nowadays have years for proverb (5)
I believe the answer is:
adage
'proverb' is the definition.
('adage' can be a synonym of 'proverb')
'nowadays have years' is the wordplay.
'nowadays' becomes 'ad'.
'have' means one lot of letters go next to another.
'years' becomes 'age' ('age' can be a synonym of 'years').
'ad'+'age'='ADAGE'
'for' is the link.
(Other definitions for adage that I've seen before include "True proverb or saying" , "Old saying; proverb" , "Proverb, maxim" , "Dictum" , "Saying, saw" .)