Crossword Genius

Three, less companionable than two? (5)

Ross

I believe the answer is:

crowd

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'two?' is the definition.
Although both the answer and definition are singular nouns, I cannot understand how they can define each other.

I cannot understand how the remainder of the clue works.

Can you help me to learn more?

(Other definitions for crowd that I've seen before include "Social set" , "Masses" , "Army" , "Flock" , "Horde" .)

I've seen this clue in the Evening Standard.
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