The most common and most likely answer to this crossword clue is the 10 letter word DOODLEBUGS
I've seen this crossword clue in The Guardian
D
O
O
D
L
E
B
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Buddy explains!
The straight part
We know that "warfare devices of 1940s" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case warfare devices of 1940s = doodlebugs.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 DOODLEBUGS mean?
DOODLEBUGS noun- The V-1 flying bomb.
- A term of endearment.
- An antlion larva (Myrmeleontidae).
- ("doodlebug tractor") An automobile converted into a cheap tractor for a small farm during the Second World War.
- A slackard or time-waster.
- An idiot.
- Someone who draws constantly.
- A divining rod or similarly intended device.
- Individual self-propelled train cars.
- A woodlouse.