Diversify (6)
'diversify' is the definition.
(I know that diversify is a kind of the vary)
This is the entire clue.
(Other definitions for vary that I've seen before include "Diversify" , "Fluctuate" , "Undergo change" , "Be dissimilar" , "Modulate" .)
(Other definitions for assort that I've seen before include "(Of genes) become distributed among cells" , "Categorize" , "Distribute in classes" , "Classify, arrange in groups" , "Class" .)