Radical devouring book without emotion (9)

I believe the answer is:

robotlike

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'radical' is the definition.
Both the definition and answer are adjectives. Perhaps they are linked in a way I don't understand?

'devouring book without emotion' is the wordplay.
'devouring' indicates putting letters inside.
'book' becomes 'b' (abbreviation for book).
'without emotion' becomes 'rootlike' (I can't justify this - if you can you should give a lot more credence to this answer).
'b' inserted into 'rootlike' is 'ROBOTLIKE'.

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I've seen this clue in The Times.

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