Shop introduces additional area for pottery (9)
I believe the answer is:
stoneware
'for pottery' is the definition.
(I've seen this in another clue)
'shop introduces additional area' is the wordplay.
'shop' becomes 'store' (synonyms).
'introduces' is an insertion indicator.
'additional' becomes 'new' (I've seen this in another clue).
'area' becomes 'a' (maths abbreviation).
'new'+'a'='newa'
'store' enclosing 'newa' is 'STONEWARE'.
(Other definitions for stoneware that I've seen before include "collection of pottery" , "Type of pottery" .)