The most common and most likely answer to this crossword clue is the 7 plus 3 letter word PEEPING TOM
I've seen this crossword clue in The Guardian
P
E
E
P
I
N
G
T
O
M
More clues leading to the result PEEPING TOM
- Mimicking bird, cat who looks for excitement?
- Spy doing tweets to his boss?
- Viewer who’s turned on first of programmes with cat that’s whizzing around
- Mimicking bird, cat who looks for excitement?
- Someone spying first of pins grasped by marker of territory?
- Cat taking a furtive look?
- Rewrite item on Pep Guardiola’s first undercover scout
- Cat mimicking bird? He looks for excitement
Buddy explains!

The straight part
We know that "Viewe/r/ who’s turned on" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case viewe/r/ who’s turned on = peeping tom.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.