The most common and most likely answer to this crossword clue is the 7 letter word SPYHOLE
S
P
Y
H
O
L
E
More clues leading to the result SPYHOLE
- She works with Poly making viewing device
- See anus as a surveillance aid?
- Les abandons hopelessly bad security device
- Way to secretly watch agent crack
- Used by Peeping Tom, 25, shy, perverted
- Alone, nursing form of hyp – it gives one a squint
- Endless publicity over plugging only a small opening for viewer
- Special unit lacking leadership takes a year to design a feature in door
- Extremely pretty hotel protected by lone method of checking callers
Buddy explains!

The straight part
We know that "surveillance aid?" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case surveillance aid? = spyhole.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 SPYHOLE mean?
SPYHOLE noun- Peephole