Recording established in Slough base (8)
I believe the answer is:
cassette
'recording' is the definition.
(thesaurus)
'established in slough base' is the wordplay.
'established' becomes 'set'.
'in' indicates putting letters inside.
'slough base' becomes 'caste' (I can't explain this - if you can you should give a lot more credence to this answer).
'set' placed inside 'caste' is 'CASSETTE'.
Can you help me to learn more?
(Other definitions for cassette that I've seen before include "Test case about tape container" , "Container that holds a magnetic tape" , "Vintage recording" , "Spool of tape" , "Recording medium" .)