Moving art is unusual (5)
I believe the answer is:
astir
'moving' is the definition.
(I've seen this in another clue)
'art is unusual' is the wordplay.
'unusual' is an anagram indicator.
'art'+'is'='artis'
'artis' anagrammed gives 'ASTIR'.
(Other definitions for astir that I've seen before include "Starting to move" , "Awake and out of bed" , "Busy" , "In motion - out of bed" , "in the land of the living" .)