The gardener likes to see it overgrown (7)
I believe the answer is:
trellis
'the gardener' is the definition.
Although both the answer and definition are singular nouns, I cannot understand how they can define each other.
I can't explain the remainder of the clue.
Can you help me to learn more?
(Other definitions for trellis that I've seen before include "Frame for creepers" , "Plant-training lattice" , "Light framework for climbing plants" , "climbers train on it" , "Latticework support for plants" .)