21a. Village in western Norway that was the scene of the Battle of Rastarkalv between Haakon the Good abd the sons of Eric Bloodaxe. (4) (=r=i).
51a. Any of a large class of organic compounds including alkaloids, hormones, sterols and vitamins. (7) (s===o==).
41d. 16th century gambling gmae that was a forerunner of poker. (7) (p=i===o).
47d. City in Veneto, birthplace of Galileo GAlilei and Livy. (5) (p===a) TIA