Falsehood associated with good English lord once (5)
I believe the answer is:
liege
'lord once' is the definition.
(feudal term for one's superior)
'falsehood associated with good english' is the wordplay.
'falsehood' becomes 'lie' (lie is a kind of falsehood).
'associated with' means one lot of letters go next to another.
'good' becomes 'g' (abbreviation).
'english' becomes 'E' (abbreviation).
'lie'+'g'+'e'='LIEGE'
(Other definitions for liege that I've seen before include "World War one battle site" , "Vassal; city in Belgium" , "Belgian city or feudal chief" , "Loyal vassal" , "Owing feudal allegiance" .)