Italian city is in middle of campaign (4)
I believe the answer is:
pisa
'italian city' is the definition.
(I've seen this before)
'is in middle of campaign' is the wordplay.
'in' indicates putting letters inside.
'middle of' says to take the centre.
The centre of 'campaign' is 'pa'.
'is' going within 'pa' is 'PISA'.
(Other definitions for pisa that I've seen before include "City on the River Arno" , "There's a marked inclination here" , "Place with leaning tower" , "Location of leaning tower" , "Tuscan city" .)