The most common and most likely answer to this crossword clue is the 9 letter word DIPHTHONG
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More clues leading to the result DIPHTHONG
- A pair of characters in lower hot pants
- Swim with hot swimwear in sound
- Two characters heard at the same time in first half of Mousetrap
- Two characters together swim with hot swimwear
- Oi, perhaps husband’s after a swim, having beachwear?
- Oi?! Pickpocket gets held up by hot pants
- Hot strip after swim for two thirds of 13
- A couple of characters sticking together
- Swim? Husband’s put on G-string — it’s two tones in one
- What’s common sounding in ‘How now brown cow’?
Buddy explains!

The straight part
We know that "A couple of characters sticking together" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case a couple of characters sticking together = diphthong.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 DIPHTHONG mean?
DIPHTHONG noun- A complex vowel sound that begins with the sound of one vowel and ends with the sound of another vowel, in the same syllable.
- A vowel digraph or ligature.