Pray, observing demon mythology (7)
I believe the answer is:
implore
'pray' is the definition.
(I know that pray can be written as implore)
'demon mythology' is the wordplay.
'demon' becomes 'imp' (I've seen this before).
'mythology' becomes 'lore' (I've seen this before).
'imp'+'lore'='IMPLORE'
'observing' is the link.
(Other definitions for implore that I've seen before include "Beg earnestly, beseech" , "Ask earnestly" , "Beg desperately" , "press" , "Beg earnestly, plead" .)