Stop fugitive finally packing trunk (5)
I believe the answer is:
cease
'stop' is the definition.
(I know that stop can be written as cease)
'fugitive finally packing trunk' is the wordplay.
'finally' suggests the final letters.
'packing' indicates putting letters inside.
'trunk' becomes 'case' (I've seen this before).
The final letter of 'fugitive' is 'e'.
'e' placed inside 'case' is 'CEASE'.
(Other definitions for cease that I've seen before include "Stop, finish" , "Stop, give over" , "Political group" , "Come to an end" , "Culminate" .)