Attack a ship with worry (6)
I believe the answer is:
assail
'attack' is the definition.
(synonyms)
'a ship with worry' is the wordplay.
'ship' becomes 'ss'.
'with' says to put letters next to each other.
'worry' becomes 'ail' (I've seen this before).
'a'+'ss'+'ail'='ASSAIL'
(Other definitions for assail that I've seen before include "Slate" , "Set upon" , "Attack, lash out" , "Criticise severely" , "Molest or harass" .)