Caligula, say (7)
I believe the answer is:
emperor
'caligula say' is the definition.
(Caligula was a Roman emperor)
This is all the clue.
(Other definitions for emperor that I've seen before include "Eg, Caesar" , "Largest type of penguin" , "Purple --; -- penguin" , "noted by Beethoven" , "Absolute ruler" .)