In organising diet, a bad start is not to one's credit (5)
I believe the answer is:
debit
'credit' is the definition.
(thesaurus)
'in organising diet a bad start' is the wordplay.
'in' indicates putting letters inside.
'organising' indicates an anagram.
'start' suggests taking the first letters.
The first letter of 'bad' is 'b'.
'diet' with letters rearranged gives 'deit'.
'deit' placed around 'b' is 'DEBIT'.
'is not to one's' is the link.
This may not be correct. Some or all of it may be part of another bit of the clue.
Can you help me to learn more?
(Other definitions for debit that I've seen before include "Accounting entry recording sums that are 5" , "Accounting entry showing amount spent" , "Enter in accounts as sum owed" , "It's not to one's credit" , "Deduct from account" .)