A peak around Northern Cheyenne, say (10)
I believe the answer is:
amerindian
'cheyenne say' is the definition.
(I know that Cheyennes is a type of Algonquian)
'a peak around northern' is the wordplay.
'peak' becomes 'meridian' (meridian can figuratively mean a peak or pinnacle).
'around' is an insertion indicator.
'northern' becomes 'n' (abbreviation e.g. N. Ireland).
'meridian' placed around 'n' is 'merindian'.
'a'+'merindian'='AMERINDIAN'
(Other definitions for amerindian that I've seen before include "could be brave" , "one of the natives" , "someone found in the New World" , "Native" , "Pontiac?" .)