A horse and a man is more than one / Hendiadys and concord
A hendiadys is a figure of speech involving two words that work together so as to establish a single, compound, complex meaning. But does this have implications in terms of concord, I wonder? Thus, if I were to say: "A person's entire strength and energy" (conceiving of strength and energy as a hendiadys, both modified by entire) would I be justified in continuing with an "is"?
Oh, by the way: I take my headline quote from Shakespeare, prompted by this article which I discovered while trying to find a solution on the Internet to the question hereby given.