So unwell — finishing early (3)
I believe the answer is:
sic
'so' is the definition.
(I've seen this before)
'unwell finishing early' is the wordplay.
'unwell' becomes 'sick' ('sick' can be similar in meaning to 'unwell').
'finishing early' means to remove the last letter.
'sick' with its last letter removed is 'SIC'.
(Other definitions for sic that I've seen before include "(Of quoted word) exactly so" , "the reading is correct" , "Written exactly thus" , "It calls attention to a quoted mistake" , "Thus among musicians" .)