The most common and most likely answer to this crossword clue is the 7 letter word HALFWIT
H
A
L
F
W
I
T
More clues leading to the result HALFWIT
- Fool spreading filth was cut short
- Idiot with success concealing dreadful flaw
- Fine intelligence associated with Prince Charlie
- Part of football match with appeal for idiot
- Charlie‘s ban on banter, perhaps …
- Fool Oscar but not Wilde?
- An idiot cycling with Alf
- Idiot is surprising success given unfortunate flaw
- Would it take another like him to be of one mind?
- Jerk‘s in 50 per cent of the West Indies diet, ultimately
Buddy explains!

The straight part
We know that "Jerk" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case jerk = halfwit.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 HALFWIT mean?
HALFWIT noun- Someone lacking in intelligence.