Senior member of a group (5)
(Other definitions for elder that I've seen before include "Senior type of tree?" , "Ancestor" , "Tree for a church senior" , "Tree; of greater age" , "Shrub - church official" .)
'senior member of a group' is the definition.
(I've seen this in another clue)
This is all the clue.
(Other definitions for doyen that I've seen before include "The most respected among experts" , "Respected expert" , "As senior statesman" , "Man who is the senior in his profession" , "Senior man of a group" .)