Bankers heading off to inform the authorities, doubtless (2,7)
I believe the answer is:
no messing
'authorities doubtless' is the definition.
I can't judge whether this defines the answer.
'bankers heading off to inform' is the wordplay.
I cannot really see how this works, but
'inform' could be 'sing' (I've seen this in other clues) and 'sing' is located in the answer.
The remaining letters 'nomes' is a valid word which might be clued in a way I don't understand.
This explanation may well be incorrect...
'the' acts as a link.
Can you help me to learn more?
(Another definition for no messing that I've seen is " Without a doubt".)