The most common and most likely answer to this crossword clue is the 7 letter word WATCHED
I've seen this crossword clue in The Guardian
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More clues leading to the result WATCHED
Buddy explains!

The straight part
We know that "under close scrutiny" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case under close scrutiny = watched.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 WATCHED mean?
WATCHED verb- To look at, see, or view for a period of time.
- To observe over a period of time; to notice or pay attention.
- To mind, attend, or guard.
- To be wary or cautious of.
- To attend to dangers to or regarding.
- To remain awake with a sick or dying person; to maintain a vigil.
- To be vigilant or on one's guard.
- To act as a lookout.
- (of a buoy) To serve the purpose of a watchman by floating properly in its place.
- To be awake.
- To be on the lookout for; to wait for expectantly.