American man on street upset Girl Guides (10)

I believe the answer is:

usherettes

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

'girl guides' is the definition.
(female ushers)

'american man on street upset' is the wordplay.
'american man' becomes 'ushe' (I am not sure about this - if you are sure you should believe this answer much more).
'on' is a charade indicator (letters next to each other).
'upset' indicates an anagram.
'street' is an anagram of 'rettes'.
'ushe'+'rettes'='USHERETTES'

Can you help me to learn more?

(Other definitions for usherettes that I've seen before include "Guides" , "female escorts" .)

I've seen this clue in The Independent.

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