Introduction of European mug following press release (7)
I believe the answer is:
preface
'introduction' is the definition.
(preface is a kind of introduction)
'european mug following press release' is the wordplay.
'european' becomes 'e' (abbreviation e.g. EU).
'mug' becomes 'face' (I've seen this before**).
'following' says to put letters next to each other.
'press release' becomes 'pr' (public relations).
'e'+'face'='eface'
'eface' put after 'pr' is 'PREFACE'.
'of' acts as a link.
(Other definitions for preface that I've seen before include "Book's introduction" , "Introductory text" , "preliminaries" , "Introduction (to a book)" , "Foreword" .)