Fraternal order (4)
I believe the answer is:
'fraternal order' is the definition.
(I've seen this in another clue)
This is all the clue.
(Other definitions for elks that I've seen before include "Large deer of Europe and N America" , "Large deer with flattened antlers" , "Moose" , "Moose(s)" , "Large deer of Northern Europe" .)