Holding his dish and the pot (7)
I believe the answer is:
Here is my best explanation:
'the pot' is the definition.
(hashish is a kind of pot)
'holding his dish' is the subsidiary indication.
'holding' means one lot of letters goes inside another.
'dish' becomes 'hash' (hash is a kind of dish).
'his' going within 'hash' is 'hashish'.
'and' is the link.
(Other definitions for hashish that I've seen before include "Hemp hallucinogen", "Resinous product of hemp smoked as drug", "Cannabis", "Drug", "Hemp drug", "Pot" and "Hallucinogenic extract of hemp".)