Dancer ____ Kelly (4)
I believe the answer is:
'dancer kelly' is the definition.
(I've seen this in another clue)
This is all the clue.
(Other definitions for gene that I've seen before include "Basic unit of heredity" , "___ Kelly, star of Singin' In The Rain, d. 1996" , "Vincent" , "affects someone's make-up" , "Hereditary unit on chromosome" .)