Unclued lights are words from a poem, its author and a relevant location. Elsewhere, ignore two accents.
 

Across

7    Music like reggae from Saskatchewan (3)
11    Carriage policeman pulled over beside hedge (6)
13    Judge meets drug addict who’s declining (7)
15    Ionian cardinal crossing Iowa (5)
16    Strong pickle’s sound (5)
17    Seminary keeps beer for Arab? (6)
18    Woman is sickly Australian (5)
21    Colour of rock bordering river (5)
22    Thoroughly noble bard’s cap (7)
27    Cover of books French author penned (7)
29    Silent historian ignores us (5)
30    Funky river has aquatic beasts (6)
32    One round child with love for Mexican snack (5)
34    Curved shaft Athens developed (6)
38   ...