They may be liquid or fixed in a ship
I believe the answer is:
assets
'they may be liquid' is the definition.
(I've seen this in another clue)
'fixed in a ship' is the wordplay.
'fixed' becomes 'set' (both can mean decided or determined).
'in' means one lot of letters goes inside another.
'ship' becomes 'SS' (prefix in ship names eg SS Great Britain).
'a'+'ss'='ass'
'set' placed within 'ass' is 'ASSETS'.
'or' is the link.
(Other definitions for assets that I've seen before include "Personal wealth" , "Valuable resources" , "Property owned by person or business" , "Total value of possessions" , "One's total goods" .)