List of runners (5)
I believe the answer is:
slate
'list of runners' is the definition.
(I've seen this in another clue)
This is all the clue.
(Other definitions for slate that I've seen before include "Bluish-grey colour" , "Grey stone; tab" , "Roof tile or pub credit" , "Stone used for roofing" , "Roofing plate" .)