One good lord finds base (7)
I believe the answer is:
ignoble
'base' is the definition.
(both can mean dishonourable or shameful)
'one good lord' is the wordplay.
'one' becomes 'i' (Roman numeral).
'good' becomes 'g' (abbreviation).
'lord' becomes 'noble' (synonyms).
'i'+'g'+'noble'='IGNOBLE'
'finds' acts as a link.
(Other definitions for ignoble that I've seen before include "Mean - of low birth" , "I belong to base sort" , "Wretched, base" , "'Base, dishonourable (7)'" , "No bilge! (anag)" .)