From necessity ran to oppressor (6)
I believe the answer is:
tyrant
'oppressor' is the definition.
(I've seen this before)
'from necessity ran to' is the wordplay.
'from' says the answer is hidden in the clue.
'TYRANT' can be found hidden inside 'necessity ran to'.
(Other definitions for tyrant that I've seen before include "Harsh and absolute ruler" , "Authoritarian" , "Person dictating" , "Despot, dictator" , "Autocrat or despot" .)