Clue to make WAG punish cleaner (7-2,6)

'cleaner' is the definition.
(liquid used to clean things)

'clue to make wag punish' is the wordplay.
'clue' becomes 'liquid' (I can't explain this - if you can you should give a lot more credence to this answer).
'to' is a charade indicator (letters next to each other) (I've seen this in other clues).
'make' indicates anagramming the letters.
'wag'+'punish'='wagpunish'
'wagpunish' anagrammed gives 'washingup'.
'liquid' after 'washingup' is 'WASHING-UP LIQUID'.