Make sense finally during case (6)
I believe the answer is:
create
'make' is the definition.
(I know that make is a more specific form of the action create by mental act)
'sense finally during case' is the wordplay.
'sense finally' becomes 'e' (I am not sure about this - if you are sure you should believe this answer much more).
'during' is an insertion indicator.
'case' becomes 'crate' (crating is a kind of casing).
'e' inserted within 'crate' is 'CREATE'.
(Other definitions for create that I've seen before include "Manufacture, bring into being" , "Compose" , "Make or invent" , "Make, Porduce" , "coin" .)