known by association

The poet denied he was part of that group/school/movement, when the only reason anyone knew his work was because of that association.

local fame

He was famous in a group of about ten poets.

guard dogs

The lesser poets of the group/school are the ones most protective, even militant, in preserving its domain. Because that domain is the only thing that gives their work value.

team player

He was happy to be a minor member of a well-known group.

one and done

I can admire an avant-garde of one. As a group an avant-garde is less attractive. Something like an art gang.