African mothers sitting by major road (5)
I believe the answer is:
masai
'african' is the definition.
(the Masai are an ethnic group of Kenya)
'mothers sitting by major road' is the wordplay.
'mothers' becomes 'mas' (ma is a kind of mother).
'sitting by' means one lot of letters go next to another.
'major road' becomes 'AI' (resembles A1, a major road).
'mas'+'ai'='MASAI'
(Other definitions for masai that I've seen before include "Highlander in Africa" , "Africans" , "E.African pastoral people" , "Member of an African pastoral people" , "East African pastoralist" .)