Empty-headed granny in outskirts of Ilfracombe (5)
I believe the answer is:
inane
'empty-headed' is the definition.
(I've seen this before)
'granny in outskirts of ilfracombe' is the wordplay.
'granny' becomes 'nan'.
'in' means one lot of letters goes inside another.
'outskirts of' says to hollow out the word (remove centre letters) (only letters on the outskirts).
'ilfracombe' with its middle removed is 'ie'.
'nan' placed inside 'ie' is 'INANE'.
(Other definitions for inane that I've seen before include "Silly or senseless" , "Thick" , "unimaginitive" , "Frivolous" , "Silly, witless" .)