Daft (5)
'daft' is the definition.
(I've seen this before)
This is all the clue.
(Other definitions for silly that I've seen before include "Goose" , "Daft" , "Ridiculous, frivolous" , "Ludicrous, foolish" , "Stupid" .)
(Other definitions for unwise that I've seen before include "Not sensible or prudent" , "Injudicious" , "Lacking sound judgement, maybe foolish" , "Ill-judged" , "Not sensible, foolish" .)