Steward originally found in bus garage, tyrant (6)
I believe the answer is:
despot
'tyrant' is the definition.
(I know that tyrant can be written as despot)
'steward originally found in bus garage' is the wordplay.
'originally' indicates taking the first letters.
'found in' is an insertion indicator.
'bus garage' becomes 'depot' (I've seen this in another clue).
The first letter of 'steward' is 's'.
's' inserted into 'depot' is 'DESPOT'.
(Other definitions for despot that I've seen before include "Tyrannical dictator" , "Autocrat" , "Posted by tyrant" , "Cruel and oppressive ruler" , "who treats others badly?" .)