It’s more than just one’s elder relatives, however! (6,4)
I believe the answer is:
family tree
'relatives however' is the definition.
I can't tell whether this defines the answer.
'it's more than just one's elder' is the wordplay.
I cannot quite see how this works, but
'more' could be 'm' and 'm' is found in the answer.
'elder' could be 'tree' (elder is a type of tree) and 'tree' is found within the answer.
'one' could be 'i' (Roman numeral) and 'i' is located in the answer.
This may be the basis of the clue (or it may be nonsense).
(Other definitions for family tree that I've seen before include "Genealogical chart" , "Personal history" , "Chart of relations" .)