Crow found in index, ultimately (5)
I believe the answer is:
exult
'crow' is the definition.
(I've seen this before)
'in index ultimately' is the wordplay.
'in' indicates the answer is hidden within the clue.
'EXULT' is hidden in the letters of 'index ultimately'.
'found' is the link.
(Other definitions for exult that I've seen before include "Gloat" , "Rejoice intensely" , "Celebrate" , "Express great joy" , "Feel or express triumph" .)