Stupidity of Italy having stripped tops off — kept fit inside (10)
I believe the answer is:
ineptitude
'stupidity' is the definition.
(ineptitude is stupidity or foolishness)
I cannot understand how the rest of the clue works.
(Other definitions for ineptitude that I've seen before include "Incompetence" , "lack of competence" , "Awkwardness, clumsiness" .)