Empty, silly (5)
I believe the answer is:
inane
I believe this clue is a double definition.
'empty' is the first definition.
(I've seen this before)
'silly' is the second definition.
(I've seen this before)
(Other definitions for inane that I've seen before include "Foolish, silly" , "Dull-witted" , "Witless and pointless" , "Absurd" , "Delirious" .)