Mostly Spanish city girl’s song (8)
I believe the answer is:
madrigal
'song' is the definition.
(madrigal is a kind of song)
'mostly spanish city girl's' is the wordplay.
I cannot quite understand how this works, but
'city' could be 'riga' (Riga is an example) and 'riga' is located in the answer.
This explanation may well be incorrect...
Can you help me to learn more?
(Other definitions for madrigal that I've seen before include "Elizabethan song" , "Old part song" , "Part-song" , "Unaccompanied song in several parts" , "Without exaggeration" .)