Region welcoming new sports venue (5)
I believe the answer is:
arena
'sports venue' is the definition.
(I've seen this before)
'region welcoming new' is the wordplay.
'region' becomes 'area' ('area' can be a synonym of 'region'**).
'welcoming' is an insertion indicator (in sense of 'inviting in').
'new' becomes 'n'.
'area' enclosing 'n' is 'ARENA'.
(Other definitions for arena that I've seen before include "battlefieId" , "Engagement ring" , "Space for public events" , "Earls Court?" , "Scene of action" .)