As a result of this blasphemy making second book (6)
I believe the answer is:
hereby
'as a result of this' is the definition.
(I've seen this before)
'blasphemy making second book' is the wordplay.
I cannot quite see how this works, but
'second' could be 're' (prefix meaning second in eg review, re-education) and 're' is found within the answer.
'book' could be 'b' (abbreviation for book) and 'b' is present in the answer.
The remaining letters 'hey' is a valid word which might be clued in a way I don't see.
This explanation may well be incorrect...
Can you help me to learn more?
(Other definitions for hereby that I've seen before include "(Formally) with this" , "Not far off" , "By this means or act" , "By this means, as result of this" , "By means of this, legally speaking" .)