Acrimony over period ship (7)
I believe the answer is:
galleon
'ship' is the definition.
(I've seen this before)
'acrimony over period' is the wordplay.
'acrimony' becomes 'gall' (both can mean bile or resentment).
'over' means one lot of letters go next to another.
'period' becomes 'eon' (eon is a kind of period).
'gall'+'eon'='GALLEON'
(Other definitions for galleon that I've seen before include "Old Spanish war-ship" , "One might sink" , "Large Spanish sailing ship of yore" , "Ship of the line" , "Large old sailing vessel" .)