Source of irritation in main road leading to the Louvre? (3,7)
I believe the answer is:
art gallery
'the louvre?' is the definition.
(the Louvre is an art gallery)
'source of irritation in main road' is the wordplay.
'source of irritation' becomes 'gall' (gall can mean irritating behaviour).
'in' indicates putting letters inside.
'main road' becomes 'artery' (I've seen this in another clue).
'gall' put into 'artery' is 'ART GALLERY'.
'leading to' is the link.
(Other definitions for art gallery that I've seen before include "Tate Modern, for example" , "Haunt of picture fanciers" , "works can be displayed here" , "Site of multiple hangings" , "Building for exhibiting pictures" .)