Unimportant person could be problem for murder detective or winemaker (6)
I believe the answer is:
nobody
'unimportant person' is the definition.
(I've seen this before)
'be problem for murder detective or winemaker' is the wordplay.
I cannot really see how this works, but
'be' could be 'body' (bodying is a kind of being) and 'body' is found in the answer.
The remaining letters 'no' is a valid word which might be clued in a way I don't see.
This explanation may well be incorrect...
'could' is the link.
Can you help me to learn more?
(Other definitions for nobody that I've seen before include "who can square the circle?" , "Person without authority or standing - hardly exists" , "Literary diarist" , "Not one person" , "Person without influence" .)