Anger shown during term at sea in galley (7)
I believe the answer is:
trireme
'galley' is the definition.
(I know that trireme is a type of galley)
'anger shown during term at sea' is the wordplay.
'anger' becomes 'ire' (ire is intense rage).
'shown during' is an insertion indicator.
'at sea' indicates an anagram.
'term' with letters rearranged gives 'trme'.
'ire' going within 'trme' is 'TRIREME'.
'in' acts as a link.
(Other definitions for trireme that I've seen before include "Ancient rowed ship" , "Oar-driven battleship of classical times" , "Roman/Greek galley" , "Galley with three banks of oars" , "Ancient vessel with three banks of oars on each side" .)