Unemotionally, will he root out a blockhead? (5)

I believe the answer is:

robot

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'unemotionally will he' is the definition.
Although both the answer and definition are singular nouns, I don't understand how one could define the other.

'root out a blockhead?' is the wordplay.
'out' indicates putting letters inside.
'a blockhead?' becomes 'b' (head letter of 'block').
'root' going around 'b' is 'ROBOT'.

Can you help me to learn more?

(Other definitions for robot that I've seen before include "Lifelike machine" , "Android, possibly" , "Automatic machine" , "Automation" , "Programmable machine" .)

I've seen this clue in the Evening Standard.

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