Comparatively prudish male enthralled by book (7)

I believe the answer is:

primmer

'comparatively prudish' is the definition.
('prim' can be a synonym of 'prudish')

'male enthralled by book' is the wordplay.
'male' becomes 'm' (common abbreviation).
'enthralled by' is an insertion indicator ('enthral' can mean 'capture').
'book' becomes 'primer' (primer is a kind of book).
'm' inserted into 'primer' is 'PRIMMER'.

I've seen this clue in The Telegraph.

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