Take possession of oceans, by sound of it (5)
I believe the answer is:
seize
'take possession' is the definition.
(I've seen this before)
'oceans by sound of it' is the wordplay.
I cannot quite understand how this works, but
'it' could be 'e' ('e' can mean 'electronic' which is similar to 'IT') and 'e' is found within the answer.
The remaining letters 'size' is a valid word which might be clued in a way I don't see.
This may be the basis of clue (or it may be nonsense).
'of' acts as a link.
Can you help me to learn more?
(Other definitions for seize that I've seen before include "Get hold of" , "Take forcibly" , "a sweet number in Grenoble, say" , "Snatch" , "Grab by force" .)