Tyrant ultimately dies in warehouse (6)
I believe the answer is:
despot
'tyrant' is the definition.
(synonyms)
'ultimately dies in warehouse' is the wordplay.
'ultimately' indicates one should take the final letters.
'in' is an insertion indicator.
'warehouse' becomes 'depot' (I've seen this before).
The final letter of 'dies' is 's'.
's' inserted inside 'depot' is 'DESPOT'.
(Other definitions for despot that I've seen before include "A ruler with unrestricted power" , "One exploiting rule" , "has first of shocks in store" , "Cruel and oppressive ruler" , "Person with more than enough power" .)