Yes, correct! Follows the girl contrary to belief (6)
I believe the answer is:
heresy
'to belief' is the definition.
(I have seen 'Unorthodox belief ' mean 'heresy' so perhaps 'belief' could also mean 'heresy')
'yes correct follows the girl' is the wordplay.
'correct' is an anagram indicator (I've seen 'correcting' mean this (the order of letters must be corrected)).
'follows' means one lot of letters go next to another.
'the girl' becomes 'her' ('her' refers to a girl or woman).
'yes' with letters rearranged gives 'esy'.
'esy' put after 'her' is 'HERESY'.
'contrary' is the link.
This may not be right. It may belong to another bit of the clue.
Can you help me to learn more?
(Other definitions for heresy that I've seen before include "Unorthodox religious opinion" , "Unbelief" , "Belief that's anathema to the orthodox" , "Religious non-conformity" , "Divergence from orthodoxy" .)