Reason to reform, being a lady (6)
I believe the answer is:
senora
'a lady' is the definition.
(I have seen 'Lady of Spain ' mean 'senora' so perhaps 'lady' could also mean 'senora')
'reason to reform' is the wordplay.
'to reform' is an anagram indicator (letters in a new form).
'reason' is an anagram of 'SENORA'.
'being' acts as a link.
(Other definitions for senora that I've seen before include "Spanish title" , "Lady overseas" , "Foreign lady; reason (anag.)" , "Lady of Spain" , "A married woman in Spain - stands to reason" .)