Criticise book that’s eclipsed the writer’s play (9)
I believe the answer is:
pantomime
'play' is the definition.
(pantomiming is a kind of playing)
'criticise book that's eclipsed the writer's' is the wordplay.
'criticise' becomes 'pan' (informal term meaning to criticise heavily).
'book' becomes 'tome' (a tome is a book).
'that's eclipsed' is an insertion indicator (some letters eclipse or cover up others).
'the writer's' becomes 'I'm' ('I am' referring to the writer of the clue).
'tome' placed around 'im' is 'tomime'.
'pan'+'tomime'='PANTOMIME'
(Other definitions for pantomime that I've seen before include "Farcical situation" , "Theatrical entertainment (usually at Christmas)" , "'Cinderella', for example" , "'He's behind you' entertainment" , "Seasonal theatre show" .)