Property is something well worth having (5)
I believe the answer is:
asset
I believe this is a double definition.
'property' is the first definition.
(asset can mean an item of property)
'something well worth having' is the second definition.
(I've seen this before)
'is' is the link.
(Other definitions for asset that I've seen before include "Item of property" , "Valuable item" , "Seats (anag.)" , "Resource; advantage" , "Something that's worth having" .)