More eager to be a mourner (6)
I believe the answer is:
keener
I believe this is a double definition.
'more eager' is the first definition.
(I've seen this in another clue)
'a mourner' is the second definition.
(I've seen this in another clue)
'to be' acts as a link.
(Other definitions for keener that I've seen before include "More wonderful" , "More enthusiastic or sharp" , "one who lives by wailing?" , "A banshee, perhaps, could be more enthusiastic" , "person mourning" .)