Make the best job of working, detection proof (2,2,10)

'detection proof' is the definition.
I know nothing about this answer so I cannot tell whether it can be defined by this definition.

'make the best job of working' is the wordplay.
I cannot quite understand how this works, but
'make' could be 'do' (do can mean to make or prepare) and 'do' is present in the answer.
'the' could be 't' (the is pronounced as a 't' sound in some dialects) and 't' is located in the answer.
'best' could be 'perfect' (associated in meaning) and 'perfect' is found in the answer.
'of' could be 'o' and 'o' is found in the answer.
'working' could be 'on' (on can mean working or activated) and 'on' is present in the answer.
A single letter 'i' remains which might be clued in a way I don't understand.
This explanation may well be incorrect...

Can you help me to learn more?