Region in Italy certainly covered by motoring organisation (4)
I believe the answer is:
asia
'region' is the definition.
(Asia is a continent)
'in italy certainly covered by motoring organisation' is the wordplay.
'in italy certainly' becomes 'si' ('yes' in Italian).
'covered by' means one lot of letters goes inside another.
'motoring organisation' becomes 'AA' (Automobile Association).
'si' put into 'aa' is 'ASIA'.
(Other definitions for asia that I've seen before include "Major land mass" , "A vast number of people have lived here" , "Large continent" , "A is A (anag)" , "Eastern continent" .)