In the end, American sailor turned up on time (2,4)
I believe the answer is:
at last
'in the end' is the definition.
(synonyms)
'american sailor turned up on time' is the wordplay.
'american' becomes 'a' (common abbreviation - e.g. in organisation names).
'sailor' becomes 'salt' (salt is a kind of sailor).
'turned up' is a reversal indicator.
'on' says to put letters next to each other (in a down clue, letters appear on others).
'time' becomes 't' (abbreviation).
'salt' written backwards gives 'tlas'.
'a'+'tlas'+'t'='AT LAST'
(Other definitions for at last that I've seen before include "Finally, having waited a long time" , "Where cobbler located" , "Eventually" , "Finally, after much delay" , "working as a cobbler?" .)