That woman's lace - it's terribly unorthodox (9)
I believe the answer is:
heretical
'unorthodox' is the definition.
(similar in meaning)
'that woman's lace it's terribly' is the wordplay.
'that woman' becomes 'her' ('her' refers to a woman).
'terribly' indicates anagramming the letters.
'lace'+'it'='laceit'
'laceit' is an anagram of 'etical'.
'her'+'etical'='HERETICAL'
(Other definitions for heretical that I've seen before include "about dissident" , "Contrary to popular belief" , "preaching falsely" , "Of unorthodox belief" , "At odds with orthodox religious beliefs" .)