A property something still has (7)
I believe the answer is:
inertia
'a property' is the definition.
(inertia is a kind of property)
'still has' is the wordplay.
'still' becomes 'inert' (not moving).
'has' becomes 'ia' (I can't justify this - if you can you should give a lot more credence to this answer).
'inert'+'ia'='INERTIA'
'something' is the link.
I am not very happy about this link. It may be part of another bit of the clue.
Can you help me to learn more?
(Other definitions for inertia that I've seen before include "Admonish" , "Disinclination to move" , "Chemical or other inactivity" , "Lack of inclination to move" , "Disinclination to change" .)