Pottery worker, one looking to keep third in kiln (6)
I believe the answer is:
Here is my best explanation:
'pottery worker' is the definition.
(I've seen this before)
'one looking to keep third in kiln' is the wordplay.
'one looking' becomes 'gazer'.
'to keep' means one lot of letters goes inside another.
'third in kiln' becomes 'l' (I can't explain this - if you can you should believe this answer much more).
'gazer' placed around 'l' is 'GLAZER'.