Silly sort bearing crown (7)
I believe the answer is:
airhead
'silly sort' is the definition.
(silly or stupid person)
'bearing crown' is the wordplay.
'bearing' becomes 'air' (I've seen this before).
'crown' becomes 'head'.
'air'+'head'='AIRHEAD'
(Other definitions for airhead that I've seen before include "Vacuous person" , "Stupid person" , "Silly" , "Numbskull" , "clot" .)