Wheelhouse
“Wheelhouses,” so sayeth Wiktionary, “are the small enclosed parts of a bridge which historically held the ship's steering wheel”. by extension of stone dead metaphor, one’s wheelhouse is one’s area of interest, competence or preference — ones bag, baby—articulated in a way that only an American would not respond to with a roundhouse slap upside the head.
Plain English Anatomy™
Noun | Verb | Adjective | Adverb | Preposition | Conjunction | Latin | Germany | Flannel | Legal triplicate | Nominalisation | Murder your darlings buzzword