Set out. It’s said you left at early start after the first sailor (8)
I believe the answer is:
tabulate
'set' is the definition.
(I know that tabulate is a type of set)
'early start after the first sailor' is the wordplay.
'start' suggests taking the first letters.
'after' says to put letters next to each other.
'the' becomes 't' (the is pronounced as a 't' sound in some dialects).
'first' means one lot of letters go next to another.
'sailor' becomes 'tabula' (I am not sure about this - if you are sure you should believe this answer much more).
The initial letter of 'early' is 'e'.
'e' after 't' is 'te'.
'te' after 'tabula' is 'TABULATE'.
'out it's said you left at' is the link.
I am not very happy about this link. Some or all of it may belong to another bit of the clue.
Can you help me to learn more?
(Other definitions for tabulate that I've seen before include "Arrange (data) in lines and columns" , "Arrange in order" , "Arrange in table or list" , "Put into rows, columns" , "Catalogue" .)