Strength equally established (5)
I believe the answer is:
asset
'strength' is the definition.
(thesaurus)
'equally established' is the wordplay.
'equally' becomes 'as' ('as' can be a synonym of 'equally').
'established' becomes 'set'.
'as'+'set'='ASSET'
(Other definitions for asset that I've seen before include "A useful thing l" , "Useful thing or person" , "Something that's worth having" , "Beneficial thing" , "One bringing benefit" .)