The business in managing money has restraint (7)
I believe the answer is:
economy
'restraint' is the definition.
(thesaurus)
'the business in managing money' is the wordplay.
I cannot quite understand how this works, but
'business' could be 'co' (short for company) and 'co' is found in the answer.
an anagram of 'money' is 'enomy' which is present in the left over letters.
No letters remain.
This may be the basis of the clue (or it may be nonsense).
'has' acts as a link.
Can you help me to learn more?
(Other definitions for economy that I've seen before include "Careful use of resources" , "Country's system of wealth creation" , "Efficient use of resources" , "Judicious expenditure of money" , "Careful expenditure" .)