Herbivore returns to plant (4)
I believe the answer is:
reed
'plant' is the definition.
(reed is a kind of plant)
I can't explain the rest of the clue.
Can you help me to learn more?
(Other definitions for reed that I've seen before include "Carol" , "Grassy plant of wet areas" , "Type of grass" , "Marsh-growing grass" , "Tall grass plant that grows in water" .)