Inside pottery, Len employed cloth (8)
I believe the answer is:
terylene
'cloth' is the definition.
(Terylene is an example)
'inside pottery len employed' is the wordplay.
'inside' indicates a hidden word.
'TERYLENE' can be found hidden inside 'pottery len employed'.
(Other definitions for terylene that I've seen before include "Polyester fibre" , "Synthetic fibre" , "Synthetic material" , "synthetic stuff" , "Fabric of polyester fibres" .)