Consolidate (5)
'consolidate' is the definition.
(I know that consolidate is a more specific form of the action the unify)
This is the entire clue.
(Other definitions for unify that I've seen before include "Get together" , "Bring together" , "Merge" , "Amalgamate" , "Form into a single group" .)
(Other definitions for merge that I've seen before include "Become one" , "Combine to form a single entity" , "Combine, coalesce" , "Come together as one" , "Mix" .)