Kelvin abandons hunting groups turning up around American naval base (5,4)

I believe the answer is:
scapa flow
'naval base' is the definition.
(I've seen this before)
'kelvin abandons hunting groups turning up around american' is the wordplay.
I cannot really see how this works, but
'around' could be 'ca' (circa) and 'ca' is found in the answer.
'american' could be 'a' (common abbreviation - e.g. in organisation names) and 'a' is found within the answer.
This may be the basis of the clue (or it may be nonsense).
Can you help me to learn more?
(Other definitions for scapa flow that I've seen before include "Wartime naval base in Orkney" , "harbour" , "Landlocked anchorage in the Orkney Islands" , "Former naval base in the Orkney Islands" .)
