Revenue including award close to unbelievable (6)
I believe the answer is:
income
'revenue' is the definition.
(thesaurus)
'including award close to unbelievable' is the wordplay.
'including' becomes 'inc'.
'award' becomes 'om' (order of merit).
'close to' indicates one should take the final letters (the close/ending of).
The last letter of 'unbelievable' is 'e'.
'inc'+'om'+'e'='INCOME'
(Other definitions for income that I've seen before include "What do you make" , "Pay earned" , "Financial gain accruing over a given period of time" , "See 12" , "Remuneration or earnings" .)