The most common and most likely answer to this crossword clue is the 7 letter word SEARING
I've seen this crossword clue in The Times
S
E
A
R
I
N
G
Buddy explains!

The straight part
We know that "Ferocious" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case ferocious = searing.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 SEARING mean?
SEARING verb- To char, scorch, or burn the surface of (something) with a hot instrument.
- To wither; to dry up.
- To make callous or insensible.
- To mark permanently, as if by burning.
- Action of the verb to sear
- Cooking food quickly at high temperature
- Very hot; blistering or boiling
- (of a pain) having a sensation of intense sudden heat