One with tanks is dipping into a quantity of liquid (8)
I believe the answer is:
aquarist
'a quantity of liquid' is the definition.
I can't tell whether this defines the answer.
'one with tanks is dipping into' is the wordplay.
'one' becomes 'a' (a thing is one thing).
'with' is a charade indicator (letters next to each other).
'tanks' becomes 'quart' (I can't explain this - if you can you should believe this answer much more).
'dipping into' is an insertion indicator.
'quart' placed around 'is' is 'quarist'.
'a'+'quarist'='AQUARIST'
Can you help me to learn more?
(Another definition for aquarist that I've seen is " one keeping fish".)