Proper nouns used around North America for chaperones (7)
I believe the answer is:
duennas
'for chaperones' is the definition.
(duenna is a kind of chaperone)
'proper nouns used around north america' is the wordplay.
'proper' becomes 'due' (what is due is what is proper or appropriate).
'nouns' becomes 'nn' (an abbreviation for noun written twice).
'used around north america' becomes 'as' (I can't justify this - if you can you should believe this answer much more).
'due'+'nn'+'as'='DUENNAS'
Can you help me to learn more?
(Another definition for duennas that I've seen is " Governesses".)