Across the pond Sam is one of the family (5)
I believe the answer is:
uncle
This clue is a double definition.
'across the pond sam' is the first definition.
(Uncle Sam)
'one of the family' is the second definition.
'is' acts as a link.
(Other definitions for uncle that I've seen before include "Slang name for pawnbroker" , "Family relation" , "Male relation; pawnbroker" , "He's related" , "Pawnbroker's nickname" .)