Start PC in Wellington? (4)

I believe the answer is:

boot

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'wellington?' is the definition.
(Wellington boots are a type of shoe)

I don't understand how the remainder of the clue works.

Can you help me to learn more?

(Other definitions for boot that I've seen before include "Heavy footwear" , "Dismiss" , "Sturdy shoe; start (a computer)" , "Car luggage space; kick" , "Sack" .)

I've seen this clue in The Sun.

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