The most common and most likely answer to this crossword clue is the 7 letter word TUT-TUT
I've seen this crossword clue in Independent
T
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More clues leading to the result TUT-TUT
- Short skirts getting shorter? Too bad!
- . Dresses made skimpier? I disapprove
- An exclamation of mild disapprobation whichever way you look at it
- Archbishop repeatedly falling short? That’s bad!
- Tenor splits ballet dress over time, that’s bad
- I don’t know a couple of old kings
- Disapproval old king briefly echoed
- Pair of kings? You could do better
- Express disapproval of Egyptian king repeatedly
Buddy explains!

The straight part
We know that "An exclamation of mild disapprobation" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case an exclamation of mild disapprobation = tut-tut.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 TUT-TUT mean?
TUT-TUT verb- To express such a sound, especially as a mild reproof
- An expression of annoyance or impatience.