Film of polar bear shot round mouth of Horton River (5,6)
I believe the answer is:
pearl harbor
'film' is the definition.
(I've seen this before)
'polar bear shot round mouth of horton river' is the wordplay.
I cannot really see how this works, but
'round' could be 'o' (round can mean a round object) and 'o' is located in the answer.
'river' could be 'ea' (I've seen this in other clues) and 'ea' is located in the answer.
This may be the basis of clue (or it may be nonsense).
'of' is the link.
Can you help me to learn more?
(Another definition for pearl harbor that I've seen is " Film".)