Without it one is utterly incompetent (5)
I believe the answer is:
voice
'utterly incompetent' is the definition.
The definition and answer can be both people as well as being singular nouns.
Maybe there's a link between them I don't understand?
'without it one' is the wordplay.
I cannot quite understand how this works, but
'it' could be 'e' ('e' can mean 'electronic' which is similar to 'IT') and 'e' is found within the answer.
'one' could be 'o' (I've seen this in other clues) and 'o' is present in the answer.
The remaining letters 'vic' is a valid word which might be clued in a way I don't understand.
This explanation may well be incorrect...
'is' acts as a link.
Can you help me to learn more?
(Other definitions for voice that I've seen before include "Articulate" , "Sound produced by humans" , "Wallop" , "Power of speech" , "Ability to speak, sing" .)