Vehicle basically involves kinetic energy at first (4)

I believe the answer is:

bike

'vehicle' is the definition.
(I know that bike is a type of single-track vehicle)

'basically involves kinetic energy at first' is the wordplay.
'at first' suggests taking the first letters.
The first letters of 'basically involves kinetic energy' is 'BIKE'.

(Other definitions for bike that I've seen before include "Bicycle (colloq.)" , "Two-wheeler (abbr)" , "Take a ride" , "Cycle (colloq.)" , "vehicle" .)

I've seen this clue in The Irish Times.

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