OP: I have a shameful confession to make: Daredevil is the only franchise that has managed to pass by my 'Ugh I don't really care much about superheroes'-feelings. By which I mean: I haven't watched The Avengers.
Though that hasn't stopped me from reading (and enjoying) a couple of crossovers because that fandom is basically inescapable so even without actively seeking out info I know enough about it to get most fics (that are mostly Matt reacting to meeting the Avengers at least).
So if anybody wants to take it in that direction I really wouldn't mind.

Having said that: I did throw a few ideas around about situations in which sign-language knowledge would be required and thought about deaf clients in general and that's certainly a possibility but I guess than you'd need more backstory than 'he had a deaf relative he occasionally talked to and so he can now hold basic conversations' because for legal council you'd need to discuss rather fine details and you shouldn't sign/say accidentally the wrong thing.

(Also: when I said I understand most of the stuff: Clint confuses me a bit. The fics I read with him had him wearing a hearing-aid? And he seems to be really good at lip-reading?)