In Rome, 50% of divorces had his backing (4)
I believe the answer is:
ovid
'divorces had his backing' is the definition.
The definition suggests a singular noun which matches the answer.
'in rome 50% of' is the wordplay.
I cannot really understand how this works, but
'of' could be 'o' and 'o' is found in the answer.
The remaining letters 'vid' is a valid word which might be clued in a way I don't see.
This may be the basis of clue (or it may be nonsense).
Can you help me to learn more?
(Other definitions for ovid that I've seen before include "Roman poet, d. about AD17" , "Void for a Latin poet" , "Metamorphoses author" , "Vi, do read the Latin poet" , "Void for old Roman poet" .)