Foolish, silly (4)
I believe the answer is:
daft
I believe this clue is a double definition.
'foolish' is the first definition.
(I've seen this before)
'silly' is the second definition.
(I've seen this before)
(Other definitions for daft that I've seen before include "Informally crazy as a brush" , "Scatty" , "like a brush?" , "Stupid" , "Informally silly or crazy" .)