One elderly relative, one with partner still (9)
I believe the answer is:
inanimate
'still' is the definition.
(I've seen this before)
'one elderly relative one with partner' is the wordplay.
'one' becomes 'i' (Roman numeral).
'elderly relative' becomes 'nan' (informal term for grandmother).
'one' becomes 'i' (Roman numeral).
'with' is a charade indicator (letters next to each other).
'partner' becomes 'mate' (synonyms).
'i'+'nan'+'i'+'mate'='INANIMATE'
(Other definitions for inanimate that I've seen before include "Not endowed with life" , "Still" , "Not living" , "Lacking life" , "Not alive" .)