Lust a pain ruining holy fellow (5,4)

I believe the answer is:

saint paul

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'holy fellow' is the definition.
The definition suggests a singular noun which matches the answer.

'lust a pain ruining' is the wordplay.
'lust a pain' can be anagrammed to 'SAINT PAUL'.
Though, I am not sure how the anagram is indicated.

Can you help me to learn more?

(Other definitions for saint paul that I've seen before include "Convert" , "apostle" , "capital of state" .)

I've seen this clue in The Sun.

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