Impressive revised arrangement of act? Clap? Sure! (11)
I believe the answer is:
spectacular
'impressive' is the definition.
(similar in meaning)
'revised arrangement of act? clap? sure' is the wordplay.
'revised arrangement of' is an anagram indicator.
'act'+'clap'+'sure'='actclapsure'
'actclapsure' anagrammed gives 'SPECTACULAR'.
(Other definitions for spectacular that I've seen before include "Sensational in appearance" , "Thrilling in effect" , "really striking" , "Splendid" , "Lavish production" .)