The most common and most likely answer to this crossword clue is the 5 plus 7 letter word TRADE SECRETS
I've seen this crossword clue in The Times
T
R
A
D
E
S
E
C
R
E
T
S
More clues leading to the result TRADE SECRETS
Buddy explains!
The straight part
We know that "Deserter acts deviously to reveal them, perhaps" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case deserter acts deviously to reveal them, perhaps = trade secrets.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.