Use train (8)

I believe the answer is:

exercise

I believe this clue is a double definition.

'use' is the first definition.
('exercise' can be a synonym of 'use')

'train' is the second definition.
(thesaurus)

(Other definitions for exercise that I've seen before include "Do it to develop skill or fitness" , "Do it to get fit" , "Task for pupil" , "Physical training or exertion" , "Gym activity?" .)

I've seen this clue in The Telegraph.

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