Julius Caesar strikes juries, capriciously in an offhand way (6)
I believe the answer is:
casual
If this is the answer, I'm afraid I cannot explain it.
Can you help me to learn more?
(Other definitions for casual that I've seen before include "Cursory or nonchalant" , "Relaxed; accidental" , "Far from formal" , "Relaxed; informal" , "Informal or nonchalant" .)