The most common and most likely answer to this crossword clue is the 8 letter word UNSHAVEN
U
N
S
H
A
V
E
N
Buddy explains!

The straight part
We know that "rather hairy" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case rather hairy = unshaven.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 UNSHAVEN mean?
UNSHAVEN adjective- Not having shaved; not shaven; untrimmed.
- Unkempt