A number following cybercrime ultimately put away (5)
I believe the answer is:
eaten
'put away' is the definition.
(I've seen this before)
'a number following cybercrime ultimately' is the wordplay.
'number' becomes 'ten' (ten is a kind of number).
'following' says to put letters next to each other.
'ultimately' indicates one should take the final letters.
The final letter of 'cybercrime' is 'e'.
'a'+'ten'='aten'
'aten' put after 'e' is 'EATEN'.
(Other definitions for eaten that I've seen before include "Gobbled" , "Crammed" , "Put away" , "absorbed in the system" , "What's taken in" .)