Wiktionary
first fiddle
n. 1 The fiddle part generally carrying the melody. 2 The player of the first fiddle part.
Usage examples of "first fiddle".
I also may be allowed to claim some merit in leading the conversation: I do not mean leading, as in an orchestra, by playing the first fiddle.
She always gets furious if she has to play second fiddle to me and yesterday I was certainly first fiddle.
He had arranged it for first fiddle, or a gitar, harp and pipes, with the occasional emphasis of a flat drum.
I explained the whole thing to them beforehand, and they said they understood -- anyhow the first fiddle did -- but they had no idea what they were doing.
Rozsa waved to the orchestra, which caused the cheering to continue, and then to the concertmaster of the orchestra, the first fiddle.