Eager to express grief (4)
I believe the answer is:
keen
I believe this clue is a double definition.
'eager' is the first definition.
(I've seen this in another clue)
'express grief' is the second definition.
(synonyms)
'to' is the link.
(Other definitions for keen that I've seen before include "Eager, enthusiastic" , "Diligent" , "Enthusiastic or sharp" , "Anxious" , "Penetrating; ardent" .)