Coach self-discipline to give up siesta outside (5)
I believe the answer is:
train
'coach' is the definition.
('train' can be a synonym of 'coach')
'self-discipline to give up siesta outside' is the wordplay.
I cannot quite understand how this works, but
'discipline' could be 'ai' (AI is an example) and 'ai' is located in the answer.
This may be the basis of clue (or it may be nonsense).
Can you help me to learn more?
(Other definitions for train that I've seen before include "Tailpiece of bridal gown" , "Coach, develop" , "Procession" , "Learn a skill etc. through practice" , "Try to get fit" .)