The most common and most likely answer to this crossword clue is the 11 letter word INDEFINABLE
I've seen this crossword clue in The Times
I
N
D
E
F
I
N
A
B
L
E
Buddy explains!

The straight part
We know that "Like word very hard to clue" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case like word very hard to clue = indefinable.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 INDEFINABLE mean?
INDEFINABLE noun- Anything that cannot be defined.
- That cannot be precisely defined or put into words.
- That defies description; indescribable.