Covers North American up, surrounded by imitations (8)
I believe the answer is:
canopies
'covers' is the definition.
(canopying is a kind of covering)
'north american up surrounded by imitations' is the wordplay.
'north american' becomes 'na'.
'up' is a reversal indicator (in down clue: letters go upwards).
'surrounded by' indicates putting letters inside.
'imitations' becomes 'copies' (I've seen this before).
'na' in reverse letter order is 'an'.
'an' placed inside 'copies' is 'CANOPIES'.
(Other definitions for canopies that I've seen before include "Coverings to shelter an area from the weather" , "Coverings over a bed, throne, etc." .)