There's no great amount of credit when taken in by a fool! (5)
I believe the answer is:
scrap
'there's no great amount' is the definition.
I can't tell whether this defines the answer.
'credit when taken in by a fool' is the wordplay.
'credit when' becomes 'cr' (abbreviation. I am not sure about the 'when' bit.).
'taken in by' indicates putting letters inside.
'a fool' becomes 'sap' ('sap' can be a synonym of 'fool').
'cr' placed inside 'sap' is 'SCRAP'.
'of' acts as a link.
Can you help me to learn more?
(Other definitions for scrap that I've seen before include "Carps (anag.)" , "Cancel; fight" , "Dispose of" , "boxing match?" , "Junk; altercation" .)