Train worker managed to keep line in design (7)
I believe the answer is:
railman
'train worker' is the definition.
I don't know anything about this answer so I can't judge whether this works.
'managed to keep line in design' is the wordplay.
'managed' becomes 'ran' (both can mean organised or was in charge of).
'to keep' is an insertion indicator.
'line' becomes 'l' (used when specifying particular lines from a poem).
'in' indicates putting letters inside.
'design' becomes 'aim' (design can mean a goal or aim).
'l' put into 'aim' is 'ailm'.
'ran' placed around 'ailm' is 'RAILMAN'.
Can you help me to learn more?
(Other definitions for railman that I've seen before include "Transport worker" , "guard, perhaps" , "Guard, say" .)