Feigning when donning something (7,2,2)

'feigning' is the definition.
I know nothing about this answer so I can't tell whether it can be defined by this definition.

'donning something' is the wordplay.
I cannot really understand how this works, but
'something' could be 'it' (I've seen this in other clues) and 'it' is present in the answer.
'donning' could be 'puttingon' ('put on' can be a synonym of 'don') and 'puttingon' is found in the leftover letters.
This accounts for all the letters.
This may be the basis of the clue (or it may be nonsense).

'when' acts as a link.

Can you help me to learn more?