Male representative with fibre (4)
I believe the answer is:
hemp
'fibre' is the definition.
(hemp is a kind of fibre)
'male representative' is the wordplay.
'male' becomes 'he'.
'representative' becomes 'mp'.
'he'+'mp'='HEMP'
'with' acts as a link.
(Other definitions for hemp that I've seen before include "Rope, cannabis, plant" , "tea" , "Source of drug" , "Marijuana" , "Plant for rope or pot" .)