Know-__; expertise
I believe the answer is:
how
(Other definitions for how that I've seen before include "In what way?" , "See 16" , "Who (anag.)" , "By what means?" , "In what manner or method?" .)
I believe the answer is:
how
(Other definitions for how that I've seen before include "In what way?" , "See 16" , "Who (anag.)" , "By what means?" , "In what manner or method?" .)