Empty pub about now's opening (6)
I believe the answer is:
barren
'empty' is the definition.
(I've seen this in another clue)
'pub about now's opening' is the wordplay.
'pub' becomes 'bar' (both are drinking establishments).
'about' becomes 're' (regarding).
'opening' says to take the initial letters.
The initial letter of 'nows' is 'n'.
'bar'+'re'+'n'='BARREN'
(Other definitions for barren that I've seen before include "Incapable of sustaining life" , "Bare and bleak" , "Unable to bear young" , "By way of illustration" , "Dull" .)