Spreadsheet producer, fast and first-rate (9)
I believe the answer is:
excellent
'first-rate' is the definition.
(I've seen this before)
'spreadsheet producer fast' is the wordplay.
'spreadsheet producer' becomes 'excel' (Microsoft Excel spreadsheet software).
'fast' becomes 'lent' (Lent is a period of fasting in Christianity).
'excel'+'lent'='EXCELLENT'
'and' acts as a link.
(Other definitions for excellent that I've seen before include "Really good, top class" , "A one" , "A-One" , "Outstanding, very good" , "Great!" .)