Owner of bark in films sails out east (6)
I believe the answer is:
Here is my best explanation:
'owner of bark in films' is the definition.
(fictional dog in several films)
'sails out east' is the subsidiary indication.
'out' indicates an anagram (out can mean wrong or inaccurate).
'east' becomes 'e' ('E' can be a synonym of 'east'**).
'sails' anagrammed gives 'lassi'.
(Other definitions for lassie that I've seen before include "Girl from Scotland and dog from film", "Young Scottish girl or Hollywood lost dog", "Movie role for several dog stars", "Scots girl - film dog", "dog in pictures", "Canine movie star", "Dog filmstar", "TV series collie dog", "Screen mutt - Scottish girl" and "Canine film star".)