The most common and most likely answer to this crossword clue is the 9 letter word SCAPEGOAT
I've seen this crossword clue in The Daily Telegraph
S
C
A
P
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T
More clues leading to the result SCAPEGOAT
- A pact goes wrong: this one takes the blame
- Southern headland attack — he’s blamed unfairly
- A pact goes wrong – he’s blamed unfairly
- Patsy’s Catholic primate, lecherous sort
- Small cloak Billy maybe gives Aunt Sally
- Person punished positioned to welcome better self
- Son dressing monkey, George, in jacket – he’ll be in trouble
- Point more than once and vigorously attack such a one?
- Can carrier attack vigorously, south of small headland?
- One made to take blame in a case got badly broken by pressure
Buddy explains!

The straight part
We know that "Fall guy" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case fall guy = scapegoat.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 SCAPEGOAT mean?
SCAPEGOAT noun- In the Mosaic Day of Atonement ritual, a goat symbolically imbued with the sins of the people, and sent out alive into the wilderness while another was sacrificed.
- Someone punished for the error or errors of someone else.
- To punish someone for the error or errors of someone else; to make a scapegoat of.
- To blame something for the problems of a given society without evidence to back up the claim.