"Singin' in the Rain" name (4)
I believe the answer is:
gene
'singin' in the rain name' is the definition.
(I've seen this in another clue)
This is the entire clue.
(Other definitions for gene that I've seen before include "and 16 Down: Rockabilly singer" , "Hereditary unit on chromosome" , "- - Kelly, dancer" , "Something got from parent < for boy" , "DNA unit" .)