OTT party type could make Tories err (9)
I believe the answer is:
roisterer
'ott party type' is the definition.
(someone who goes over the top at a party)
'make tories err' is the wordplay.
'make' is an anagram indicator.
'tories'+'err'='torieserr'
'torieserr' is an anagram of 'ROISTERER'.
'could' is the link.
(Other definitions for roisterer that I've seen before include "Noisy merrymaker" , "Noisy reveller" , "Living it up" , "He's pushing the boat out" , "noisy party animal" .)