Sentence:  It turns out that the driver of the red Ferrari that caused the crash wasn't, as I first guessed, a youngster, but a 60-year-old. Clearly, he had energy to spare, which was more than could be said about a panel I listened to around the same time as the crash. Indeed, someone <WSD>hissed</WSD> in my ear during a First Magazine awards ceremony in London's imposing Marlborough House on 7 December: "What we need is more old white men on the stage." 
Meaning of the word marked with <WSD> tags:  To utter (something) with a hissing sound.