Black Prince lifted rubbish (4)
I believe the answer is:
blah
'rubbish' is the definition.
(I've seen this in another clue)
'black prince lifted' is the wordplay.
'black' becomes 'b' (as in pencil classifications).
'prince' becomes 'hal' (name for Prince Henry in Shakespeare's histories).
'lifted' shows that the letters should be reversed in order (going up in down clue).
'hal' back-to-front is 'lah'.
'b'+'lah'='BLAH'
(Other definitions for blah that I've seen before include "Rhubarb" , "Stupid 20" , "Insipid" , "Pretentious nonsense" , "Claptrap" .)