The most common and most likely answer to this crossword clue is the 8 letter word ESPALIER
E
S
P
A
L
I
E
R
More clues leading to the result ESPALIER
- Train Earl to get more canny touring Pennsylvania
- Tree forced flat to sprawl among scattered pears
- Framework for growth regularly gets less healthy-looking, I admitted
- Playfully leap and rise where climbing’s intended
- Trainer’s sixth sense leads to hesitation by old boxer
- Setback arises, involving one trainer of climbers
- Rose climbs here, displaying pearlies
- Training and support for horticulturists!
- Pear lies off the wall – leaving this?
- Garden frame, where rotten pear lies
Buddy explains!

The straight part
We know that "trellis" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case trellis = espalier.The cryptic/wordplay part
In cryptic crossword there's often an wordplay/cryptic part as well.This part involves a more complex hint, such as an anagram, homophone, hidden word, etc.
Sadly, We don't have an explanation for this specific crossword clue yet.
What does ESPALIER mean?
ESPALIER noun- A latticework used to shape or train the branches of a tree or shrub into a two-dimensional ornamental or useful design, as along a wall or fence.
- A plant that has been shaped in this manner.
- A row of plants that have been shaped in this manner.
- To train a plant in this manner.