fire in the one’s belly

　Nobody could have predicted - and to the best of my knowledge nobody did - that Rupert Murdoch, the cunning Australian with news in his veins and unquenchable fire in his belly, would be a seller. Not like this anyway.
　It took the charm of Bob Iger to make it happen. They met over the summer. Iger undoubtedly has one of the most impressive track records of any chief executive in media, and the other qualities that have led to his being talked as a future presidential candidate.
　Interviewed this morning, he didn't deny political ambition. But the extension of his contract to 2021, to the delight of investors, and the fact that James Murdoch's future is uncertain - he wasn't mentioned in the statements from either company - exposes earlier stories about Rupert's younger son becoming boss of Disney for the nonsense they always were.
　That story was presumably briefed out by the Murdoch camp, and it is possible that he could yet end up with a senior position at Disney. But Iger's diplomatically chosen words on the subject today, saying that "he will be discussing whether there is a role for [James] - or not - at our company" were not flattering. (Skip the rest)

http://www.bbc.com/news/entertainment-arts-42361410

　今回取り上げる表現は、fire in the one’s belly です。
　この表現を『ジーニアス英和大辞典』(大修館)でみると、「勃勃たる野心、滾る決意」とあります。fire は多くの意味を持つ語として知られています。同書によれば、fire には代表的な「火」という意味から、動詞で「解雇する、(非難など)を浴びせる」という意味もあることがわかります。
　今回の表現の中では、名詞の「激情、熱情、熱意、熱心」という意味が当てはまります。また、belly は「腹」の意味を持ちます。日本語の「腹」を調べると、「（腹の内面にあるものとして）心。考え。感情。気持ち。また、度量や度胸、気力もいう。」(『日本語表現インフォ』http://hyogen.info/word/6391810)とあります。日本語で「腹を据える」や「腹を括る」といった表現に表れています。よって今回の表現は直訳すると「腹の中にある熱意」、つまり「野心」ということになります。煮えたぎっているようなイメージですね。(OkaUchi)