Supreme pimp exposed American in danger (8)
I believe the answer is:
imperial
'supreme' is the definition.
(thesaurus)
'pimp exposed american in danger' is the wordplay.
'exposed' means to look at the middle letters (outside letters removed).
'american' becomes 'a' (common abbreviation - e.g. in organisation names).
'in' means one lot of letters goes inside another.
'danger' becomes 'peril' (peril is a kind of danger).
The middle letters of 'pimp' are 'im'.
'a' placed within 'peril' is 'perial'.
'im'+'perial'='IMPERIAL'
(Other definitions for imperial that I've seen before include "Relating to empire" , "small tufted beard" , "Of UK weights and measures" , "Magnificent; small pointed beard" , "Majestic - not metric" .)