"First of all ..." (3)
(Other definitions for one that I've seen before include "Sole; identical" , "Smallest whole number" , "Hour after midnight" , "Lowest cardinal number" , "Figure" .)
'first of all?' is the definition.
(I've seen this in another clue)
This is the entire clue.
(Other definitions for adam that I've seen before include "Biblical first man" , "First man of Genesis" , "First fruit-eater" , "Biblical first human" , "father figure" .)