Plain structure represented on the genes (10)
I believe the answer is:
stonehenge
'plain structure' is the definition.
(stone structure on Salisbury Plain)
'represented on the genes' is the wordplay.
'represented' is an anagram indicator.
'on'+'the'+'genes'='onthegenes'
'onthegenes' anagrammed gives 'STONEHENGE'.
(Other definitions for stonehenge that I've seen before include "heritage site" , "rock group" , "Ancient monument site" , "prehistoric pillars" , "Megalithic monument on Salisbury Plain" .)