Poets dared at last to write about this tyrant (6)
I believe the answer is:
despot
'this tyrant' is the definition.
(synonyms)
'poets dared at last to write about' is the wordplay.
'at last' suggests the final letters.
'to write about' is an anagram indicator (I've seen 'written about' mean this (letters moved about before being rewritten)).
The last letter of 'dared' is 'd'.
'poets'+'d'='poetsd'
'poetsd' with letters rearranged gives 'DESPOT'.
(Other definitions for despot that I've seen before include "Possibly 4 [CZAR]" , "Tyrant, dictator" , "Cruel and oppressive ruler" , "Tyranical dictator" , "Person with more than enough power" .)