Runners enlist doctor after training (8)
I believe the answer is:
tendrils
'runners' is the definition.
(parts of a plant which run along the ground)
'enlist doctor after training' is the wordplay.
I cannot quite understand how this works, but
'doctor' could be 'tend' (I've seen this in another clue) and 'tend' is found within the answer.
This may be the basis of clue (or it may be nonsense).
Can you help me to learn more?
(Other definitions for tendrils that I've seen before include "They're used by climbers" , "Slender stems with which some plants attach themselves for support" , "Feelers or slender curls" , "Curlers" , "Organs of climbing plants" .)