The most common and most likely answer to this crossword clue is the 6 plus 9 letter word WALRUS MOUSTACHE
I've seen this crossword clue in The Daily Telegraph
W
A
L
R
U
S
M
O
U
S
T
A
C
H
E
More clues leading to the result WALRUS MOUSTACHE
Buddy explains!
The straight part
We know that "overhanging growth" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case overhanging growth = walrus moustache.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.