Clue: Sponge John having picked up a bit of fluff (5)
Answer: LOOFA
Explanation: Definition: Sponge
A charade of LOO (toilet, 'john') plus FA, a reversal ('up' in a down light) of 'a' plus F ('bit of **F**luff'). I hope we have exhausted the dispute over the definition of LOOFA as 'sponge' – it came up not so long ago.