Building over frozen soil sees river rising (7)
I believe the answer is:
rotunda
'building' is the definition.
(I know that rotunda is a type of building)
I don't understand the rest of the clue.
(Other definitions for rotunda that I've seen before include "Round domed room" , "Round building or hall" , "Italian Pantheon, for instance" , "Round domed building" , "Do a turn (anag) -- circular domed building" .)