Fool carrying round detergent (4)
I believe the answer is:
soap
'detergent' is the definition.
(thesaurus)
'fool carrying round' is the wordplay.
'fool' becomes 'sap' ('sap' can be a synonym of 'fool'**).
'carrying' means one lot of letters goes inside another.
'round' becomes 'o' (round can mean a round object).
'sap' going around 'o' is 'SOAP'.
(Other definitions for soap that I've seen before include ". . . . opera, sentimentalised radio or tv series" , "type of TV programme" , "Long running TV series" , "Cleansing TV serial drama" , "Popular TV programme (which cleans?)" .)