Political opponent from Byzantium (4)
I believe the answer is:
anti
'political opponent' is the definition.
'anti' can be an answer for 'opponent' (someone opposed to something). I'm not certain of the 'political' bit.
'from byzantium' is the wordplay.
'from' says the answer is hidden in the clue.
'ANTI' can be found hidden inside 'byzantium'.
Can you help me to learn more?
(Other definitions for anti that I've seen before include "Against, informally" , "not favoured" , "An opponent - opposed to party policy, etc" , "'No' voter" , "Someone opposed (to a policy?)" .)