Primitive tribe finally allowed a man to keep servants (9)
I believe the answer is:
elemental
'primitive' is the definition.
(synonyms)
'tribe finally allowed a man to keep servants' is the wordplay.
'finally' indicates one should take the final letters.
'allowed' becomes 'let' (to let is to allow or permit).
'a man' becomes 'al' ().
'to keep' is an insertion indicator.
'servants' becomes 'men' (man is a kind of servant).
The final letter of 'tribe' is 'e'.
'let'+'al'='letal'
'letal' placed around 'men' is 'lemental'.
'e'+'lemental'='ELEMENTAL'
(Other definitions for elemental that I've seen before include "key" , "Of nature's powers" , "Pertaining to weather or to first principles" , "being like Mercury?" , "Related to the powers of nature" .)