A lot of prayer captivates god (8)
I believe the answer is:
plethora
'a lot' is the definition.
'prayer captivates god' is the wordplay.
'prayer' becomes 'plea' (plea is a kind of prayer).
'captivates' indicates putting letters inside (inserted letters are captured or captivated).
'god' becomes 'thor' (Thor is an example).
'plea' enclosing 'thor' is 'PLETHORA'.
'of' is the link.
(Other definitions for plethora that I've seen before include "More than enough" , "Excessive quantity" , "Large number" , "Superabundance" , "Embarrassment" .)