Foam coming forth unexpectedly (5)

I believe the answer is:

froth

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'foam coming' is the definition.
'froth' can be an answer for 'foam' ('froth' can be a synonym of 'foam'). I am not sure about the 'coming' bit.

'forth unexpectedly' is the wordplay.
'unexpectedly' indicates anagramming the letters.
'forth' with letters rearranged gives 'FROTH'.

Can you help me to learn more?

(Other definitions for froth that I've seen before include "Effervesce" , "Lather" , "Spume or foam" , "Mass of small bubbles" , "Small bubbles on a liquid" .)

I've seen this clue in the Evening Standard.

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