Time on association creates connection (7)
I believe the answer is:
linkage
'connection' is the definition.
(I know that linkage is a type of connection)
'time on association' is the wordplay.
'time' becomes 'age' (an age is a period of time).
'on' means one lot of letters go next to another.
'association' becomes 'link' (I've seen this in another clue).
'age' after 'link' is 'LINKAGE'.
'creates' acts as a link.
(Other definitions for linkage that I've seen before include "where the join is" , "Leaking (anag)" , "Part of mechanism" , "Connection, bond" , "Connection, coupling" .)