Prefix for "binary" (3)
I believe the answer is:
non
'prefix for binary' is the definition.
(I've seen this in another clue)
This is the entire clue.
(Other definitions for non that I've seen before include "Negative French word" , "Prefix meaning negative" , "- - -stick" , "Prefix meaning not or none" , "Prefixed negation of a word" .)