Gladden greatly (5)
I believe the answer is:
elate
'gladden greatly' is the definition.
(I've seen this in another clue)
This is all the clue.
(Other definitions for elate that I've seen before include "Doctor suitor to Anne Page (MWOW)" , "Make joyful and proud" , "cheer" , "Excite" , "Delight" .)