Seen in fjord, marine creature gets surprised expression from Jock (3,4)
I believe the answer is:
sea loch
'creature gets surprised expression from jock' is the definition.
I don't know anything about this answer so I cannot tell whether it can be defined by this definition.
'seen in fjord marine' is the wordplay.
I cannot really understand how this works, but
'marine' could be 'sea' (both can mean 'of the sea') and 'sea' is located in the answer.
The remaining letters 'loch' is a valid word which might be clued in a way I don't see.
This may be the basis of the clue (or it may be nonsense).
Can you help me to learn more?
(Other definitions for sea loch that I've seen before include "Lake-like arm of salt water in Scotland" , "Arm of the ocean (Scotland)" , "Scottish water" .)