Old ruler needing some vodka is erratic (6)

I believe the answer is:

kaiser

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'old ruler' is the definition.
'Kaiser' can be an answer for 'ruler' (Kaiser is an example). I'm unsure of the 'old' bit.

'some vodka is erratic' is the wordplay.
'some' indicates the answer is hidden within the clue (some of the parts of the word are used).
'KAISER' can be found hidden inside 'vodka is erratic'.

'needing' is the link.

Can you help me to learn more?

(Other definitions for kaiser that I've seen before include "Old German emperor like Bill" , "Austrian bigwig" , "Old German emperor, pre-Hitler" , "Emperor of Austria or Germany until 1918" , "Former German emperor" .)

I've seen this clue in The Sun.

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