Expedition dispensing with a fine outfit (4)
I believe the answer is:
ring
'outfit' is the definition.
(thesaurus)
'expedition dispensing with a fine' is the wordplay.
'expedition' becomes 'airing' (airing is a kind of expedition).
'dispensing with' suggests deleting specific letters.
'a fine' becomes 'ai' (resembles A1, informal term for top quality).
'airing' with 'ai' taken out is 'RING'.
(Other definitions for ring that I've seen before include "Surround; reverberate" , "Phone; round" , "Make sound like phone" , "Phone; circle" , "Marriage token" .)