Period film's enthralling southern scenery (5,3)
I believe the answer is:
stage set
'scenery' is the definition.
(I've seen this in another clue)
'period film's enthralling southern' is the wordplay.
'period' becomes 'stage' (e.g. a stage in history).
'film' becomes 'ET' (E.T. the Extra-Terrestrial).
'enthralling' is an insertion indicator.
'southern' becomes 's' (abbreviation).
'stage'+'et'='stageet'
'stageet' enclosing 's' is 'STAGE SET'.
(Other definitions for stage set that I've seen before include "dramatic backdrop" , "Scenery and furniture" , "play ready to start" , "Theatre scenery etc" .)