Drama training by new enclosure (7)
I believe the answer is:
playpen
'enclosure' is the definition.
(playpen is a kind of enclosure)
'drama training by new' is the wordplay.
'drama' becomes 'play' ('play' can be a synonym of 'drama'**).
'training' becomes 'pe'.
'by' says to put letters next to each other.
'new' becomes 'n'.
'play'+'pe'+'n'='PLAYPEN'
(Other definitions for playpen that I've seen before include "device to capture the young" , "Portable enclosure for tots" , "Limited room for amusement" , "Nipper stuck here" , "Baby enclosure" .)