Flustered by what newly betrothed had on (3,3,8)

I believe the answer is:

hot and bothered

I'm a little stuck... Click here to teach me more about this clue!

'flustered' is the definition.
(I know that flustered can be written as hot and bothered)

'newly betrothed had on' is the wordplay.
'newly' is an anagram indicator.
'betrothed'+'had'+'on'='betrothedhadon'
'betrothedhadon' is an anagram of 'HOT AND BOTHERED'.

'by what' acts as a link.
This may not be correct. Some or all of it may belong to another bit of the clue.

Can you help me to learn more?

I've seen this clue in the Sydney Morning Herald.

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