I act subsequently as a worshipper of a cult image (8)
I believe the answer is:
idolater
'a worshipper of a cult image' is the definition.
I can't tell whether this definition defines the answer.
'i act subsequently' is the wordplay.
'act' becomes 'do' (to do is to act or execute a task).
'subsequently' becomes 'later' (subsequently means later on).
'i'+'do'+'later'='IDOLATER'
'as' acts as a link.
Can you help me to learn more?
(Other definitions for idolater that I've seen before include "Besotted admirer" , "A person who worships idols" , "Tailored like pagan worshipper" , "No orthodox believer" , "I put off" .)