Trip into a plastered wall (9)
I believe the answer is:
partition
'wall' is the definition.
(I've seen this before)
'trip into a plastered' is the wordplay.
'plastered' indicates an anagram (plastered can informally mean drunk).
'trip'+'into'+'a'='tripintoa'
'tripintoa' with letters rearranged gives 'PARTITION'.
(Other definitions for partition that I've seen before include "Screen" , "wall" , "Separation (of a country) into separate nations" , "Barrier" , "segregation" .)