Account including a single corrected number? (9)
I believe the answer is:
analgesic
'number?' is the definition.
(I've seen this before)
'account including a single corrected' is the wordplay.
'account' becomes 'ac' (abbreviation).
'including' means one lot of letters goes inside another.
'corrected' indicates anagramming the letters.
'a'+'single'='asingle'
'asingle' with letters rearranged gives 'nalgesi'.
'ac' placed around 'nalgesi' is 'ANALGESIC'.
(Other definitions for analgesic that I've seen before include "number" , "Painkilling" , "result is soothing" , "medicament" , "A medicine used to relieve pain" .)