Crossword Genius

Potter wasn’t one earthenware piece short: delight! (6)

Ross

I believe the answer is:

muggle

'potter wasn't one' is the definition.
(a non-magical person in the Harry Potter books)

'earthenware piece short delight' is the wordplay.
'earthenware piece' becomes 'mug' (piece of crockery).
'short' means to remove the last letter.
'delight' becomes 'glee' (I've seen this before).
'glee' with its last letter taken away is 'gle'.
'mug'+'gle'='MUGGLE'

(Another definition for muggle that I've seen is " Person who is not a wizard".)

I've seen this clue in The Times.
Want a hint initially instead of a full solution? Install my app