ἐξ ὀνύχων λέοντα τεκμαίρεσθαι → judge by the claws, judge by a slight but characteristic mark, small traits give the clue to the character of a person, deduce something from a small indication, identify a lion from its claws
P. and V. κακόν, τό, δυσπραξία, ἡ, ἀγών, ὁ, Ar. and V. πόνοι, οἱ; see trouble.