Leading lady interrupts ham and fobs off surprise performance (5,3)

I believe the answer is:

flash mob

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'surprise performance' is the definition.
The definition suggests a singular noun which matches the answer.

'leading lady interrupts ham and fobs off' is the wordplay.
'leading' says to take the initial letters (the leading letter of the word).
'interrupts' is an insertion indicator.
'and' is a charade indicator (letters next to each other).
'off' indicates an anagram.
The initial letter of 'lady' is 'l'.
'ham' put after 'fobs' is 'fobsham'.
'fobsham' is an anagram of 'fashmob'.
'l' inserted within 'fashmob' is 'FLASH-MOB'.

Can you help me to learn more?

(Other definitions for flash mob that I've seen before include "Sudden mass of people" , "streakers?" , "Unexpected gathering" , "Ad hoc group assembled to do something unusual in a public place" .)

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

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