Exclusion of some tribes — basically, bigotry! (9)
I believe the answer is:
ostracism
'exclusion' is the definition.
(ostracism is a kind of exclusion)
'of some tribes basically bigotry' is the wordplay.
'basically' indicates taking the first letters (the first letter could be its root or base).
'bigotry' becomes 'racism' (I've seen this in another clue).
The initial letters of 'of some tribes' is 'ost'.
'ost'+'racism'='OSTRACISM'
(Other definitions for ostracism that I've seen before include "transferring to Coventry?" , "isolation" , "Boycott" , "Shunning" , "Banishment" .)