Sort of bear in LA between two rivers (5)
I believe the answer is:
polar
'sort of bear' is the definition.
'la between two rivers' is the wordplay.
'two rivers' can mean two replacements for 'river'.
'between' means one lot of letters goes inside another.
'river' becomes 'Po' (the river Po in Italy).
'river' becomes 'r' (abbreviation).
'po'+'r'='por'
'la' placed inside 'por' is 'POLAR'.
'in' is the link.
(Other definitions for polar that I've seen before include "Directly opposed" , "Relating to icy regions" , "Of the highest latitude" , "Of the cold regions" , "in Antarctica, say" .)