Manly man backed copper with rank (9)
I believe the answer is:
masculine
'manly' is the definition.
(associated in meaning)
'backed copper with rank' is the wordplay.
'backed' becomes 'mas' (I can't explain this - if you can you should believe this answer much more).
'copper' becomes 'Cu' (Cu is the chemical symbol for copper).
'with' means one lot of letters go next to another.
'rank' becomes 'line'.
'mas'+'cu'+'line'='MASCULINE'
'man' is the link.
I am not very happy about this link. It may be part of another bit of the clue.
(Other definitions for masculine that I've seen before include "Butch" , "Calumnies about macho type" , "Calumnies about male equality" , ""Man" is clue (anag)" , "Possessing qualities of a man" .)