Sailor finds the French competent (4)
I believe the answer is:
able
'competent' is the definition.
(similar in meaning)
'sailor finds the french' is the wordplay.
'sailor' becomes 'ab' (abbreviation for able seaman).
'finds' is a charade indicator (letters next to each other).
'the french' becomes 'le' ('the' in French).
'ab'+'le'='ABLE'
(Other definitions for able that I've seen before include "... was I ere I saw Elba (palindrome)" , "Fitted" , "Bright" , "With the required capacities" , "Capable or proficient" .)