The most common and most likely answer to this crossword clue is the 5 letter word BARMY
I've seen this crossword clue in The Guardian
B
A
R
M
Y
More clues leading to the result BARMY
- British fighting force is nuts
- Land forces to be led by bishop is bonkers
- Boozer Mudd’s bonkers!
- Royal Marines seen in the sea inlet – but not all there
- Horse nibbling Mr Turner’s nuts
- British military force that’s not all there
- Mad reservists?
- Crazy bandleader joining the forces
- Idiotic host supporting top of bill
- British forces around the bend
Buddy explains!
The straight part
We know that "not all there" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case not all there = barmy.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 BARMY mean?
BARMY adjective- Odd, strange, or crazy.
- Containing barm, i.e. froth from fermented yeast.