Girl heading off African people in ring (7)
I believe the answer is:
annulus
'ring' is the definition.
(technical term for ring-shaped object)
'girl heading off african people' is the wordplay.
'girl' becomes 'ann' (woman's name).
'heading off' means to remove the first letter.
'african people' becomes 'Zulus' (the Zulus are an African people).
'zulus' with its first letter taken away is 'ulus'.
'ann'+'ulus'='ANNULUS'
'in' is the link.
(Other definitions for annulus that I've seen before include "Ring-shaped object" , "Ring-shaped structure" .)