Main stems of plants (6)
I believe the answer is:
stalks
'main stems of plants' is the definition.
(I've seen this before)
This is the entire clue.
(Other definitions for stalks that I've seen before include "Main stems of plants" , "Shadows with plant stems" , "'Stems, plant supports (6)'" , "Tracks or pursues stealthily" , "Hunts" .)