Count time mother's without (6)
I believe the answer is:
matter
'count' is the definition.
(synonyms)
'time mother's without' is the wordplay.
'time' becomes 't' (abbreviation).
'mother' becomes 'mater' (old-fashioned term for mother).
'without' is an insertion indicator.
't' placed into 'mater' is 'MATTER'.
(Other definitions for matter that I've seen before include "Subject; be important" , "Stuff - be of importance" , "Substance - signify" , "Be of significance" , "It has mass and occupies space" .)