Plant that grows up a support (7)
I believe the answer is:
climber
'plant that grows up a support' is the definition.
(I've seen this before)
This is the entire clue.
(Other definitions for climber that I've seen before include "Edward Whymper, for example" , "Plant such as ivy" , "Mountaineer" , "Plant that grows up a support" , "Bonnington" .)