Shoot the messenger (6)
I believe the answer is:
runner
This clue is a double definition.
'shoot' is the first definition.
(plant shoot that goes along the ground)
'messenger?' is the second definition.
(someone who carries a message)
'the' is the link.
(Other definitions for runner that I've seen before include "Kind of bean is a fast mover" , "Athlete - mat - bean" , "Participant in a race" , "Smuggler; a bean" , "Branch from the base of plant that produces new plants" .)