Skilful line not seen in Dutch crockery (4)
I believe the answer is:
deft
'skilful' is the definition.
(I've seen this before)
'line not seen in dutch crockery' is the wordplay.
'line' becomes 'l'.
'not seen in' suggests deleting specific letters.
'dutch crockery' becomes 'Delft' (pottery originating from Delft in the Netherlands).
'delft' with 'l' taken away is 'DEFT'.
(Other definitions for deft that I've seen before include "Quick and skilful in movement" , "Quick and skillful" , "Quick, neatly skilful" , "Adroit, dexterous" , "Nimble-fingered" .)