Sink or swim (4)
I believe this is a double definition.
'sink' is the first definition.
(I know that sink can be written as dip)
'swim' is the second definition.
(dip can mean a brief swim)
'or' acts as a link.
(Other definitions for dip that I've seen before include "Go down" , "A quick bathe" , "Thick sauce; brief swim" , "Pickpocket" , "Immerse briefly in liquid" .)
'sink or swim' is the definition.
(I've seen this in another clue)
This is the entire clue.
(Other definitions for verb that I've seen before include "A word that conveys action" , "Predicate of a sentance (4)" , "The predicate of a sentence" , "Word such as run, make, or do" , "'In grammar, it denotes action (4)'" .)