Lacklustre send-up of Shakespeare (4)
I believe the answer is:
drab
'lacklustre' is the definition.
(thesaurus)
'send-up of shakespeare' is the wordplay.
'send-up of' is a reversal indicator.
'shakespeare' becomes 'bard' (I've seen this before).
'bard' written backwards gives 'DRAB'.
(Other definitions for drab that I've seen before include "Dismal < slattern" , "Gloomy" , "Rather dull" , "Tedious" , "Dull and colourless" .)