The mark of a finished writer? (4,4)
I believe the answer is:
full stop
'the mark' is the definition.
(full stop is a kind of mark)
'a finished writer?' is the wordplay.
I cannot quite see how this works, but
'finished' could be 'stop' (I've seen this before) and 'stop' is present in the answer.
The remaining letters 'full' is a valid word which might be clued in a way I don't see.
This explanation may well be incorrect...
'of' acts as a link.
Can you help me to learn more?
(Other definitions for full stop that I've seen before include "'Punctuation mark (4,4)'" , "Punctuation mark - period" , "period in America" , "Period of sentence" , "finalised" .)