An autocrat in the city ran things (6)
I believe the answer is:
tyrant
'an autocrat' is the definition.
('tyrant' can be a synonym of 'autocrat')
'in the city ran things' is the wordplay.
'in' says the answer is hidden in the clue.
'TYRANT' is hidden in the letters of 'city ran things'.
(Other definitions for tyrant that I've seen before include "bully - with 17d" , "Despotic ruler" , "Totalitarian" , "Autocrat or despot" , "taskmaster" .)