Comanche trained to become bus drivers (8)
I believe the answer is:
coachmen
'bus drivers' is the definition.
'coachmen' can be an answer for 'drivers' (coachman is a kind of driver). I am not sure about the 'bus' bit.
'comanche trained' is the wordplay.
'trained' is an anagram indicator (to train can mean to grow something into a shape).
'comanche' with letters rearranged gives 'COACHMEN'.
'to become' acts as a link.
Can you help me to learn more?
(Other definitions for coachmen that I've seen before include "Carriage drivers" , "riders" .)