Pre-eminent male, remaining, elderly relative (11)
I believe the answer is:
grandmother
'elderly relative' is the definition.
'grandmother' can be an answer for 'relative' (grandmother is a kind of relative). I'm not certain of the 'elderly' bit.
'pre-eminent male remaining' is the wordplay.
'pre-eminent' becomes 'grand' (I can't justify this - if you can you should believe this answer much more).
'male' becomes 'm' (common abbreviation).
'remaining' becomes 'other' (similar in meaning).
'grand'+'m'+'other'='GRANDMOTHER'
Can you help me to learn more?
(Other definitions for grandmother that I've seen before include "Female ancestor" , "See 22" , "Relation" , "Older relative" , "Mum's mum" .)