Criminal to free her thus? (9)
I believe the answer is:
therefore
'thus?' is the definition.
(I know that thus can be written as therefore)
'criminal to free her' is the wordplay.
'criminal' is an anagram indicator.
'to'+'free'+'her'='tofreeher'
'tofreeher' is an anagram of 'THEREFORE'.
(Other definitions for therefore that I've seen before include "In consequence" , "Consequently - for that reason" , "has a triangular formation in maths?" , "It follows" , "Ergo" .)