E.g. Napoleon's comment suggesting why tattoo is impossible (4)
I believe the answer is:
oink
'e g napoleon's comment suggesting why' is the definition.
I can't judge whether this defines the answer.
'tattoo is impossible' is the wordplay.
I cannot really see how this works, but
'tattoo' could be 'ink' (ink can informally mean a tattoo) and 'ink' is found in the answer.
A single letter 'o' 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?
(Other definitions for oink that I've seen before include "it might be in a pen one hears" , "Piggish noise" , "Animal sound" , "Pig's noise" , "Swine sound" .)