It's unpleasant removing pets from year book (6)

I believe the answer is:

annual

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'year book' is the definition.
(I've seen this before)

I don't understand the remainder of the clue.

(Other definitions for annual that I've seen before include "Occuring once a year" , "Twelve-monthly" , "Type of year book" , "Happening once each year" , "plant > book" .)

I've seen this clue in the Irish Times (Crosaire) and the Irish Times.

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