Prime minister hosts various cronies on top-class stage (10)
I believe the answer is:
proscenium
'stage' is the definition.
(proscenium is a kind of stage)
'prime minister hosts various cronies on top-class' is the wordplay.
'prime minister' becomes 'PM' (synonyms).
'hosts' indicates putting letters inside (inserted letters are welcomed or hosted).
'various' indicates anagramming the letters.
'on' is a charade indicator (letters next to each other).
'top-class' becomes 'U' (as in U and non-U speech).
'cronies'+'u'='croniesu'
'croniesu' with letters rearranged gives 'rosceniu'.
'pm' enclosing 'rosceniu' is 'PROSCENIUM'.
(Another definition for proscenium that I've seen is " Front part of stage".)