Manoeuvring seaward — to drink (4,5)
I believe the answer is:
soda water
'drink' is the definition.
(soda water is a kind of drink)
'manoeuvring seaward to' is the wordplay.
'manoeuvring' indicates anagramming the letters.
'seaward'+'to'='seawardto'
'seawardto' anagrammed gives 'SODA WATER'.
(Other definitions for soda water that I've seen before include "Possible splash" , "Fizzy drink" , "Fizzy mixer" , "Aerated drink" , "Carbonated drink" .)