Somewhat boorish cry? (3)

I believe the answer is:

boo

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'cry?' is the definition.
(I know that boo is a type of cry)

I can't explain the rest of the clue.

(Other definitions for boo that I've seen before include "Exclamation of disapproval" , "Catcall" , "Cry of disapproval as at villain" , "Shout of dislike" , "I don't like that!" .)

I've seen this clue in the Evening Standard.

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