Best two or three, for example? (5)
I believe the answer is:
prime
'best' is the definition.
(I've seen this before)
I don't understand how the rest of the clue works.
Can you help me to learn more?
(Other definitions for prime that I've seen before include "Prepare to fire - first" , "Choice" , "2017, for example" , "First-rate; type of number" , "Best quality, perhaps of beef" .)