Yes, there are measures. Whether they are consistent or useful is subjective.
A probabilistic parser like https://demos.explosion.ai/displacy or https://cloud.google.com/natural-language/ returns one parse. But under the hood, it had a few candidates and just chose the most probable one.
If the even the first candidate had a low probability then we could say that the sentence was "hard to parse".
If the second candidate had almost the same probability as the first one, likewise.
If the first parse is in fact wrong then tautologically it was (too) hard for that parser.
If it is grammatically correct but semantically improbable then we enter into a philosophical question about what the parsing task includes.
There are also many metrics you can extract from the returned tree itself, like depth.