Chromosome component (3)
(Other definitions for dna that I've seen before include "Substance that stores genetic information in body" , "Deoxyribonucleic acid (abbreviation)" , "Genetic material often used by police" , "Substance in chromosomes that stores genetic information, used by police" , "Bodily substance that stores genetic information - police use it to identify" .)
'chromosome component' 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 "A segment of DNA" , "Bodily factor controlling heredity" , "Vincent" , "Unit of heredity significance" , "Hereditary unit on chromosome" .)