Step around arbiter's introduction (7)
I believe the answer is:
preface
'introduction' is the definition.
(I know that Preface is a preface)
'step around arbiter's' is the wordplay.
'step' becomes 'pace' (pace is a kind of step).
'around' indicates putting letters inside.
'arbiter' becomes 'ref' (I've seen this in other clues).
'pace' enclosing 'ref' is 'PREFACE'.
(Other definitions for preface that I've seen before include "Introduction (to a book)" , "Opening words" , "preliminaries" , "Book's introduction" , "Foreword" .)