Kidnap the sailor by the canal (6)
I believe the answer is:
abduct
'kidnap' is the definition.
(I know that kidnap can be written as abduct)
'sailor by the canal' is the wordplay.
'sailor' becomes 'ab' (abbreviation for able seaman).
'by' is a charade indicator (letters next to each other).
'the canal' becomes 'duct' (synonyms).
'ab'+'duct'='ABDUCT'
'the' acts as a link.
(Other definitions for abduct that I've seen before include "Kidnap, carry person off by force" , "Snatch away" , "Take (someone) away by force" , "Kidnap, make off with" , "Remove by force" .)