Shoemaker's model left before end of day, finally (6)
I believe the answer is:
lastly
'finally' is the definition.
(synonyms)
'shoemaker's model left before end of day' is the wordplay.
'shoemaker's model' becomes 'last' (I've seen this in another clue).
'left' becomes 'l' (common abbreviation).
'before' means one lot of letters go next to another.
'end of' suggests the final letters.
The last letter of 'day' is 'y'.
'last'+'l'+'y'='LASTLY'
(Other definitions for lastly that I've seen before include "In conclusion" , "In the end" , "Finally, to conclude with" .)