Lecturer joining end of impromptu party game (4)
I believe the answer is:
ludo
'game' is the definition.
(ludo is a kind of game)
'lecturer joining end of impromptu party' is the wordplay.
'lecturer' becomes 'l' (abbreviation for lecturer).
'joining' is a charade indicator (letters next to each other).
'end of' indicates one should take the final letters.
'party' becomes 'do' (do is a kind of party).
The last letter of 'impromptu' is 'u'.
'l'+'u'+'do'='LUDO'
(Other definitions for ludo that I've seen before include "Simple board game, involving dice" , "Children's board game" , "Type of board game" , "Traditional board game" , "Loud sort of board game with dice and counters" .)