Presumably, what can be distilled in spirit from the Duke of York, or is that still illegal? (6)
I believe the answer is:
poteen
'spirit from the duke of york or is that still illegal?' is the definition.
'poteen' can be an answer for 'spirit' (I've seen this before). I am unsure of the remainder of the definition.
'presumably what can be distilled' is the wordplay.
I cannot really understand how this works, but
'can' could be 'pot' ('pot' can be a synonym of 'can') and 'pot' is located in the answer.
The remaining letters 'een' is a valid word which might be clued in a way I don't understand.
This explanation may well be incorrect...
'in' acts as a link.
Can you help me to learn more?
(Other definitions for poteen that I've seen before include "Illegal alcohol made from potatoes and other mash" , "Illegal Irish spirit made in still" , "Illegal drink" , "illicit booze" , "Illicit whiskey (Irish)" .)