Efforts to describe something idiomatically with the use of metaphor—a word or phrase that figuratively provides an analogy—more than once in a sentence will likely distractingly interfere with reading comprehension, so avoid using more than one metaphor in a sentence, or at least ensure that they are complementary. Discussions after each example in this post explain the difficulty of using two metaphors, and revisions suggest a solution.
1. What you hear symbolizes something ominous—impending danger lurking just beneath the surface, which has been hanging over our heads in recent years.
The metaphors in this sentence come at the reader from both directions, with an allusion to subterranean peril and an indirect reference to the anecdote of the sword of Damocles, in which a king suspends a sword over a courtier’s head by a single hair to teach the man a lesson about the peril of being in a position of power. To avoid this discordance, the metaphors should be consistent in imagery: “What you hear symbolizes something ominous—impending danger lurking just beneath the surface, which has percolating in recent years.” (Percolating is also a metaphor, but such one-word analogies embedded in our language do not distract as easily as more vivid imagery, and the verb is concordant with the preceding metaphor.)
2. These actions resulted in a significant redirection of market focus and gave the firms a ringside seat when the proverbial music stopped.
“A ringside seat” refers to achieving a privileged position (literally, a front-row seat at a boxing match), and the phrase about music alludes to surviving a round of the game of musical chairs, in which competitors circle a group of chairs that numbers one less than the number of participants and vie to obtain a seat when music that is briefly played suddenly ceases, causing one person to be disqualified in each round. Although both metaphors deal, in a sense, with attainment of privilege, the contexts are different, and one is best abandoned in favor of the other: “These actions resulted in a significant redirection of market focus and gave the firms a ringside seat when that shift occurred.”
3. The same division within the party that derailed healthcare reform could also rear its head with respect to tax reform.
The reference to figurative derailment is at odds with the clichéd metaphor of a threatening creature preparing to strike. Again, sacrifice one metaphor for another (preferably, replacing the cliché with a straightforward verb): “The same division within the party that derailed healthcare reform could also occur with respect to tax reform.” (An attempt to match the derailment reference with another train-related metaphor will only call attention to the symmetry at the expense of the point of the sentence.)