>(slang) Extremely good at something (usually a video game).
Neither the Merriam-Webster dictionary nor the Cambridge dictionary[0] list meaning 4, further hinting that it is a use that is mostly occurring in niche online communities. Note that I'm not saying meaning 4 is incorrect[1]. There's no such thing. Words is words. Usage is meaning. But I think I am justified in my belief that it is still relatively uncommon.
[0] The OED wanted money to show me their list of meanings.
[1] Although it is almost assuredly a mishearing of "crack".
