A ship taking trouble to attack (6)
I believe the answer is:
assail
'attack' is the definition.
('assail' can be a synonym of 'attack')
'a ship taking trouble' is the wordplay.
'ship' becomes 'ss'.
'taking' says to put letters next to each other.
'trouble' becomes 'ail' ('ail' can be a synonym of 'trouble').
'a'+'ss'+'ail'='ASSAIL'
'to' acts as a link.
(Other definitions for assail that I've seen before include "Attack, lash out" , "Assault, attack" , "Maybe mug" , "Trouble" , "Go for" .)