"My Fair Lady” lyricist (6)
I believe the answer is:
lerner
'my fair lady lyricist' is the definition.
(I've seen this in another clue)
This is all the clue.
(Other definitions for lerner that I've seen before include "Musical librettist" , "American lyricist" , "4 1 [THANK HEAVENS FOR LITTLE GIRLS] writer" , "US lyricist" .)