Wizard dispenses with fifty old sheep (6)
I believe the answer is:
merino
'sheep' is the definition.
(breed of sheep)
I cannot understand how the rest of the clue works.
Can you help me to learn more?
(Other definitions for merino that I've seen before include "Can this sheep be found in Rome?" , "Sheep with fine quality fleece" , "Fine-wool sheep" , "The sheep provides fine wool" , "Sheep with fine soft wool" .)