I need clout, fooling around — it's in my DNA (10)
I believe the answer is:
nucleotide
'it's in my dna' is the definition.
(compound in DNA)
'i need clout fooling around' is the wordplay.
'fooling around' indicates an anagram.
'i'+'need'+'clout'='ineedclout'
'ineedclout' with letters rearranged gives 'NUCLEOTIDE'.
(Other definitions for nucleotide that I've seen before include "Type of organic molecule" , "material of DNA" , "Phosphate and sugar linked in this compound; once dilute (anag.)" .)