First of surprises in store for autocrat (6)
I believe the answer is:
despot
'for autocrat' is the definition.
(synonyms)
'first of surprises in store' is the wordplay.
'first of surprises' becomes 's' (1st letter of 'surprises').
'in' indicates putting letters inside.
'store' becomes 'depot' (depot can mean a store or warehouse).
's' put into 'depot' is 'DESPOT'.
(Other definitions for despot that I've seen before include "Tyrant, oppressor" , "Cruel and oppressive dictator" , "Posted (anag)" , "monster?" , "Caesar for one" .)