The most common and most likely answer to this crossword clue is the 4 plus 3 plus 5 plus 2 plus 2 letter word IT’S ALL GREEK TO ME
I've seen this crossword clue in The Guardian
I
T
â
€
™
S
A
L
L
G
R
E
E
K
T
O
M
E
More clues leading to the result IT’S ALL GREEK TO ME
Buddy explains!
The straight part
We know that "that I can’t grasp" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case that i can’t grasp = it’s all greek to me.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.