The same ship is wrecked by stress (8)
I believe the answer is:
emphasis
'stress' is the definition.
(I know that stress can be written as emphasis)
'the same ship is wrecked' is the wordplay.
'is wrecked' indicates anagramming the letters.
'same'+'ship'='sameship'
'sameship' with letters rearranged gives 'EMPHASIS'.
'by' acts as a link.
(Other definitions for emphasis that I've seen before include "Intensity of expression" , "Stress given to a word" , "Accentutation" , "Stress - misshape (anag)" , "Force" .)