A Liberal receiving duke without preparation (2-3)
I believe the answer is:
ad-lib
'without preparation' is the definition.
(I've seen this before)
'a liberal receiving duke' is the wordplay.
'liberal' becomes 'lib'.
'receiving' is an insertion indicator.
'duke' becomes 'd' (abbreviation).
'a'+'lib'='alib'
'alib' enclosing 'd' is 'AD-LIB'.
(Other definitions for ad-lib that I've seen before include "Depart from the text" , "Improvise" , "freely" , "without restraint" , "Speak off the cuff" .)