Sailor with paddle departs on a boat? (6)
I believe the answer is:
aboard
'on a boat?' is the definition.
(aboard a boat)
'sailor with paddle departs' is the wordplay.
'sailor' becomes 'ab' (abbreviation for able seaman).
'with' means one lot of letters go next to another.
'paddle' becomes 'oar' (I've seen this in another clue).
'departs' becomes 'd' (common abbreviation e.g. train timetables).
'ab'+'oar'+'d'='ABOARD'
(Other definitions for aboard that I've seen before include "in a car" , "on base" , "Embarked on (a ship)" , "on a ferry?" , "Alongside" .)