Assert sea-creature's in control of current (5)
I believe the answer is:
claim
'assert' is the definition.
(I know that claim is a more specific form of assert)
'sea-creature's in control of current' is the wordplay.
I cannot really understand how this works, but
'control' could be 'aim' (aim is a kind of control) and 'aim' is located in the answer.
This explanation may well be incorrect...
Can you help me to learn more?
(Other definitions for claim that I've seen before include "Formal request" , "title" , "Allege" , "Assertion of ownership etc" , "Call" .)