Older relative
(Other definitions for elder that I've seen before include "Church official; tree" , "Older person - one's senior" , "Kind of tree or sage person" , "Patriarch" , "Senior churchperson" .)
'older relative' is the definition.
(I've seen this before)
This is all the clue.
(Other definitions for grannie that I've seen before include "old lady" , "senior citizen, perhaps" , "Older relative" .)