A referee turns around holding party hat (6)
I believe the answer is:
fedora
'hat' is the definition.
(I know that fedora is a type of hat)
'a referee turns around holding party' is the wordplay.
'referee' becomes 'ref' (synonyms).
'turns around' is a reversal indicator (I've seen 'turning around' mean this).
'holding' is an insertion indicator.
'party' becomes 'do' (do is a kind of party).
'a'+'ref'='aref'
'aref' written backwards gives 'fera'.
'fera' going around 'do' is 'FEDORA'.
(Other definitions for fedora that I've seen before include "Brimmed hat with creased crown" , "Felt hat, dented lengthwise" , "Headgear" , "top fashion" , "Cover for head" .)