Returning genetic material as well (3)
I believe the answer is:
and
'as well' is the definition.
(I've seen this in other clues)
'returning genetic material' is the wordplay.
'returning' says the letters should be written in reverse.
'genetic material' becomes 'DNA' (deoxyribonucleic acid).
'dna' back-to-front is 'AND'.
(Other definitions for and that I've seen before include "It connects words, clauses or sentences" , "It's used to connect words, clauses or sentences" , "See 20" , "moreover" , "Together with" .)