Coach, according to linesman, always calling (6)
I believe the answer is:
career
'calling' is the definition.
(synonyms)
'coach according to linesman always' is the wordplay.
I cannot really understand how this works, but
'coach' could be 'car' (as in a train coach or car) and 'car' is found in the answer.
'always' could be 'eer' (poetic way of saying ever) and 'eer' is present in the answer.
No letters remain.
This may be the basis of the clue (or it may be nonsense).
Can you help me to learn more?
(Other definitions for career that I've seen before include "Rush headlong" , "One's business path through life" , "Run wildly" , "Progress of working life" , "Employment history" .)