Take ages to be a member (6)
I believe the answer is:
belong
'be a member' is the definition.
'take ages' is the wordplay.
'take' becomes 'be' (being is a kind of taking).
'ages' becomes 'long'.
'be'+'long'='BELONG'
'to' is the link.
(Other definitions for belong that I've seen before include "Appertain" , "to have a home" , "Have a proper place (in)" , "Be attached" , "Be owned by" .)