The most common and most likely answer to this crossword clue is the 7 letter word BRACKEN
B
R
A
C
K
E
N
More clues leading to the result BRACKEN
- Brother Livingstone infiltrated by a Conservative plant
- Supporternext to Livingstone, possibly, is a plant
- Stand amid Scottish mountain ferns …
- Fern‘s underwear caught by Barbie’s partner
- With switch of direction, denigrate hillside growth
- Feature of heath and mountain crossed by timeless path
- Banker abroad taking in cold hillside feature?
Buddy explains!

The straight part
We know that "hillside growth" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case hillside growth = bracken.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 BRACKEN mean?
BRACKEN noun- Any of several coarse ferns, of the genus Pteridium, that form dense thickets; often poisonous to livestock.
- An area of countryside heavily populated by this fern.