The most common and most likely answer to this crossword clue is the 12 letter word SMOKESCREENS
I've seen this crossword clue in The Guardian
S
M
O
K
E
S
C
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E
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N
S
More clues leading to the result SMOKESCREENS
Buddy explains!
The straight part
We know that "They hide the truth" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case they hide the truth = smokescreens.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 SMOKESCREENS mean?
SMOKESCREENS noun- Smoke used as a disguise, mask or cover, as of troops in battle.
- Anything used metaphorically to conceal or distract.