Eager to display grief (4)
I believe the answer is:
keen
I believe this is a double definition.
'eager' is the first definition.
(I've seen this before)
'display grief' is the second definition.
(keen can mean to wail with grief)
'to' acts as a link.
(Other definitions for keen that I've seen before include "cry" , "Sharp - avid" , "Diligent" , "Sharp - lament" , "Eager; dirge" .)