second fiddle

English Thesaurus

1. a secondary role or function (noun.act)

hypernym	:	function, office, part, role,
definition	:	the actions and activities assigned to or required or expected of a person or group (noun.act)

2. someone who serves in a subordinate capacity or plays a secondary role (noun.person)

hypernym	:	foot soldier, subordinate, subsidiary, underling,
definition	:	an assistant subject to the authority or control of another (noun.person)