Unexpected form of pub art (6)
I believe the answer is:
abrupt
'unexpected' is the definition.
(thesaurus)
'form of pub art' is the wordplay.
'form of' indicates anagramming the letters (the letters need to be in another 'form').
'pub'+'art'='pubart'
'pubart' with letters rearranged gives 'ABRUPT'.
(Other definitions for abrupt that I've seen before include "Curt; precipitous" , "using minimal language?" , "Curt and brief" , "Curt and short" , "Sudden; precipitous" .)