Men take years to make an establishment (6)
I believe the answer is:
menage
'an establishment' is the definition.
The answer and definition can be both groups as well as being singular nouns.
Maybe you can see a link between them that I don't see?
'men take years' is the wordplay.
'take' is a charade indicator (letters next to each other).
'years' becomes 'age' (period of many years).
'men'+'age'='MENAGE'
'to make' is the link.
Can you help me to learn more?
(Other definitions for menage that I've seen before include "family group" , "live together" , "Persons of household" , "Members of a household" , "Social unit living together" .)