Corrupt Ernest accepts small bribe (9)
I believe the answer is:
sweetener
'bribe' is the definition.
(thesaurus)
'corrupt ernest accepts small' is the wordplay.
'corrupt' indicates anagramming the letters.
'accepts' indicates putting letters inside.
'small' becomes 'wee' ('wee' can be similar in meaning to 'small').
'ernest' anagrammed gives 'stener'.
'stener' going around 'wee' is 'SWEETENER'.
(Other definitions for sweetener that I've seen before include "pill to replace sugar" , "Extra inducement" , "carrot" , "Saccharin, for example" , "Eg, sugar" .)