Fool races round West Indies (4)
I believe the answer is:
twit
'fool' is the definition.
(thesaurus)
'races round west indies' is the wordplay.
'races' becomes 'tt' (Isle of Man Tourist Trophy races).
'round' indicates putting letters inside.
'west indies' becomes 'wi'.
'tt' enclosing 'wi' is 'TWIT'.
(Other definitions for twit that I've seen before include "Twerp" , "dunce" , "Nincompoop" , "Silly person (colloq.)" , "Stupid person" .)