Same ship; different stress (8)
I believe the answer is:
emphasis
'stress' is the definition.
(synonyms)
'same ship different' is the wordplay.
'different' is an anagram indicator (letters placed in a different order).
'same'+'ship'='sameship'
'sameship' is an anagram of 'EMPHASIS'.
(Other definitions for emphasis that I've seen before include "Weight" , "Stress given to a word" , "Importance; priority" , "Stress, accentuation" , "Special importance or significance" .)