Depends on the UK, really. And whether you consider the UK "Europe." I can vaguely see the US and an Imperial Germany with interests in South America coming to blows, and the rest of South America falling in, but for it to be against all of Europe (and not a total cakewalk for Europe), a number of things have to go wrong on both sides.
Some possibilities...
Financial crisis in Britain which sees cuts in the RN, with ships sold off to the US and others? That would weaken Europe's navy enough that a naval fight with the US could be on more even grounds. (The US could conceivably faced off the UK in a naval arms race with some PODs, but not so sure of Britain AND all the navies of Europe, unless some of those navies follow governments in exile.)
A more "total" victory for either side in WW1, so that come 1940 the winners can force the losers to fight alongside them, or be occupied and then see their resources used in the war.