"The Rain in Spain” lyricist (6)
I believe the answer is:
lerner
'the rain in spain lyricist' is the definition.
(I've seen this in another clue)
This is the entire clue.
(Other definitions for lerner that I've seen before include "Musical librettist" , "US lyricist" , "American lyricist" , "4 1 [THANK HEAVENS FOR LITTLE GIRLS] writer" .)