May be mounted in a ring? (7)
I believe the answer is:
picador
'may' is the definition.
Although both the answer and definition are singular nouns, I cannot see how one could define the other.
I don't understand the rest of the clue.
Can you help me to learn more?
(Other definitions for picador that I've seen before include "fighter with lance" , "Mounted bullfighter with a lance" , "ringfighter" , "Cop raid to get bullfighter on horseback" , "Animal killer" .)