Untainted English in tribal group (5)
I believe the answer is:
clean
'untainted' is the definition.
(I've seen this in another clue)
'english in tribal group' is the wordplay.
'english' becomes 'E' (abbreviation).
'in' means one lot of letters goes inside another.
'tribal group' becomes 'clan' (I've seen this in another clue).
'e' placed into 'clan' is 'CLEAN'.
(Other definitions for clean that I've seen before include "Pure, hygienic" , "thoroughly" , "Clear (of drugs)" , "Honest" , "Untarnished" .)