Sinister Tory lord returning at start of year (6)
I believe the answer is:
creepy
'sinister' is the definition.
(I know that sinister can be written as creepy)
'tory lord returning at start of year' is the wordplay.
'tory' becomes 'c'.
'lord' becomes 'peer' (peer is a kind of lord).
'returning' shows that the letters should be reversed in order.
'at' means one lot of letters go next to another.
'start of year' becomes 'y'.
'peer' written backwards gives 'reep'.
'c'+'reep'+'y'='CREEPY'
(Other definitions for creepy that I've seen before include "Eerie, uncanny" , "Mysterious" , "Producing fear and unease" , "Causing feelings of fear or repulsion" , "Disturbing, crawly" .)