Donor putting lock on account after complaint about Nigel's capital (12)
I believe the answer is:
benefactress
'donor' is the definition.
(thesaurus)
'lock on account after complaint about nigel's capital' is the wordplay.
I cannot really understand how this works, but
'lock' could be 'ress' (I've seen this in another clue) and 'ress' is found in the answer.
'account' could be 'ac' (abbreviation for account) and 'ac' is located in the answer.
This explanation may well be incorrect...
'putting' is the link.
Can you help me to learn more?
(Other definitions for benefactress that I've seen before include "one who does good" , "Donor, patron" , "Generous female donor" , "One gives" , "Lady patron" .)