A plant holder? (7)
I believe the answer is:
tendril
'a plant holder?' is the definition.
(I've seen this in another clue)
This is the entire clue.
(Other definitions for tendril that I've seen before include "Thread-like part by which climbing plant clings" , "Slender thread-like appendage of a plant" , "Natural thread climbing plants produce to attach to a support" , "Clinging part of a plant" , "Slender stem on twining plants" .)