The most common and most likely answer to this crossword clue is the 11 letter word FLOUNDERING
I've seen this crossword clue in The Times
F
L
O
U
N
D
E
R
I
N
G
Buddy explains!
The straight part
We know that "likely to fail" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case likely to fail = floundering.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 FLOUNDERING mean?
FLOUNDERING verb- To flop around as a fish out of water.
- To make clumsy attempts to move or regain one's balance.
- To act clumsily or confused; to struggle or be flustered.
- To be in serious difficulty.
- The act of one who flounders; a clumsy struggle.