Given something to eat, admitting rule is unsound (6)
I believe the answer is:
flawed
'unsound' is the definition.
(thesaurus)
'given something to eat admitting rule' is the wordplay.
'given something to eat' becomes 'fed' (given food).
'admitting' means one lot of letters goes inside another (admit can mean to welcome in or accept).
'rule' becomes 'law' (law is a kind of rule).
'fed' enclosing 'law' is 'FLAWED'.
'is' acts as a link.
(Other definitions for flawed that I've seen before include "wrong" , "With imperfections" , "with a hole in it" , "Containing blemish or imperfection" , "Imperfect" .)