My tailor's questionable ethics (8)
I believe the answer is:
morality
'ethics' is the definition.
(synonyms)
'my tailor's questionable' is the wordplay.
'questionable' is an anagram indicator.
'my'+'tailor'='mytailor'
'mytailor' is an anagram of 'MORALITY'.
(Other definitions for morality that I've seen before include "Behaviour in terms of right and wrong" , "Principles of good and bad for my tailor" , "Ethical conduct" , "Ethics" , "Ethical system" .)