Sick? Not very, miss (4)
I believe the answer is:
omit
'miss' is the definition.
(I know that miss can be written as omit)
'sick? not' is the wordplay.
I cannot really see how this works, but
'not' could be 'o' (I've seen this in other clues) and 'o' is present in the answer.
The remaining letters 'mit' is a valid word which might be clued in a way I don't understand.
This explanation may well be incorrect...
'very' acts as a link.
Can you help me to learn more?
(Other definitions for omit that I've seen before include "Fail to mention" , "Take out" , "Exclude; forget to include" , "Neglect to include" , "Leave out or undone" .)