Lecture using new media to entertain 150 (7)
I believe the answer is:
declaim
'lecture' is the definition.
(thesaurus)
'new media to entertain 150' is the wordplay.
'new' indicates anagramming the letters.
'to entertain' is an insertion indicator.
'150' becomes 'cl' (roman numerals).
'media' with letters rearranged gives 'deaim'.
'deaim' placed around 'cl' is 'DECLAIM'.
'using' is the link.
(Other definitions for declaim that I've seen before include "Make a rhetorical speech" , "Speak imposingly" , "Make a set speech" , "Deliver (words) impressively" , "Speak dramatically" .)