From study, observes characteristic area linking seas (7,6)
I believe the answer is:
denmark strait
'from study' is the definition.
I can't tell whether this defines the answer.
'observes characteristic area linking seas' is the wordplay.
I cannot really see how this works, but
'observes' could be 'marks' (marking is a kind of observing) and 'marks' is located in the answer.
'characteristic' could be 'rai' (I've seen this in another clue) and 'rai' is located in the answer.
'area' could be 'den' (den is a kind of area) and 'den' is located in the answer.
This may be the basis of the clue (or it may be nonsense).
Can you help me to learn more?
(Another definition for denmark strait that I've seen is " area between oceans".)