Categorize (6)
I believe the answer is:
assort
'categorize' is the definition.
(I know that assort is a more specific form of categorize)
This is all the clue.
(Other definitions for assort that I've seen before include "Distribute in classes" , "(Of genes) become distributed among cells" , "Categorise" , "Classify, arrange in groups" , "Class" .)