Q - and many more variants.

Les Fromull mentions Knocking Up a meal. A similar but different construct would be Knock Out - which has nothing to do with pugilism, but to produce or manufacture something rapidly and in quantity. A Tin Pan Alley songwriter might knock out a song before lunch and another before bedtime. A potter might knock out a dozen pots an hour.

Door knockers - brass striker and plate, are still used on doors. They certainly have not been superceded by bells.
I wouldn't call a person who knocks on doors "a knocker" - a "bloody nuisance" perhaps. Officially, if trying to sell, they would be a "hawker" and notices on gates do read "No Hawkers", although I don't recall ever having heard the term in oral usage.

"Knockers" is also slang for a female bosom.

As for the winkle. Take some sand from a beach and soak it in sea water. Wrap an elastic band round it and sprinkle with brown malt vinegar. Place in mouth and chew for five minutes. You would have a fairly accurate simulation of the mollusc as a culinary delicacy.

I am with Anne Lister in the opinion that there is no such word as wankle in the "English" language and someone is mistaken in thinking there is.

Quack!
GtD.