The most common and most likely answer to this crossword clue is the 14 letter word BROBDINGNAGIAN
I've seen this crossword clue in The Guardian
B
R
O
B
D
I
N
G
N
A
G
I
A
N
Buddy explains!

The straight part
We know that "Enormous" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case enormous = brobdingnagian.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 BROBDINGNAGIAN mean?
BROBDINGNAGIAN adjective- Of or pertaining to Brobdingnag.
- Enormous, huge, far larger than is customary for such a thing.