What does the word 「ごねだした」 mean?

Question

I'm not sure if it is a nuance of the word 「ごねる」 which means to make difficulties or to grumble.

Here is the sentence containing the word.

なんせ... 青山が五人の選手の中に入れてくれってごねだしたのは知ってるんだ

Answer 1

ごね出した【だした】 means "started to grumble." 出す is one of the syntactic compound verb elements. After the masu-stem of a verb, it means "to begin to ～", similarly to ～始める. See: What is the difference between 出す and 始める when used as a suffix?