Chap filled with need to slander (7)
I believe the answer is:
blacken
'slander' is the definition.
(thesaurus)
'chap filled with need' is the wordplay.
'chap' becomes 'ben' (man's name).
'filled with' means one lot of letters goes inside another.
'need' becomes 'lack' (to lack something is to be in need of it).
'ben' enclosing 'lack' is 'BLACKEN'.
'to' is the link.
(Other definitions for blacken that I've seen before include "Soil" , "Besmirch" , "Char" , "Damage (a reputation)" , "Tarnish" .)