Plain movement in audition (6)
I believe the answer is:
steppe
'plain' is the definition.
(steppe is a kind of plain)
'movement in audition' is the wordplay.
'movement' becomes 'step' (step is a kind of movement).
'in audition' indicates a 'sounds like' (homophone) clue (audition can mean hearing).
'step' is a homophone of 'STEPPE'.
(Other definitions for steppe that I've seen before include "Dry area of grassland in southeast Europe and Siberia" , "crosses Siberia" , "Treeless plain of Russia" , "plain territory" , "Edxtensive plain" .)