Girl in West Side Story fails to start song (4)
I believe the answer is:
aria
'song' is the definition.
(aria is a kind of song)
'girl in west side story fails to start' is the wordplay.
I cannot quite see how this works, but
'side' could be 'r' (abbreviation for right) and 'r' is present in the answer.
The remaining letters 'aia' is a valid word which might be clued in a way I don't see.
This may be the basis of clue (or it may be nonsense).
Can you help me to learn more?
(Other definitions for aria that I've seen before include "Operatic tune" , "complex song" , "Refrain" , "Vocal solo in a cantata etc" , "Song for solo voice from an oratorio, cantata etc" .)