Mind mishap no good for sailor (10)
I believe the answer is:
midshipman
'for sailor' is the definition.
(I've seen this before)
'mind mishap no good' is the wordplay.
'no good' indicates an anagram (no good can mean faulty or defective).
'mind'+'mishap'='mindmishap'
'mindmishap' anagrammed gives 'MIDSHIPMAN'.
(Other definitions for midshipman that I've seen before include "Easy for one" , "Probationary naval officer's rank" , "Royal Navy rank" , "Probationary rank of young naval officer" , "Sailor" .)