
1) Druid stone 2) Druid stone of England 3) English druid stone 
Found on 
https://www.crosswordclues.com/clue/sarsen

 Sarsen stones are sandstone blocks found in quantity in the United Kingdom on Salisbury Plain, the Marlborough Downs, in Kent, and in smaller quantities in Berkshire, Essex, Oxfordshire, Dorset and Hampshire. They are the post-glacial remains of a cap of Cenozoic silcrete which once covered much of southern England, a dense, hard rock created from...
Found on 
http://en.wikipedia.org/wiki/Sarsen

• (n.) One of the large sandstone blocks scattered over the English chalk downs; -- called also sarsen stone, and Druid stone.
Found on 
http://thinkexist.com/dictionary/meaning/sarsen/

(from the article `Stonehenge`) ...it, all interrupted by an entrance gap on the northeast, leading to a straight path called the Avenue. At the centre of the circle is a stone ...
Found on 
http://www.britannica.com/eb/a-z/s/33
 Sar'sen  noun
Sar'sen  noun [ Etymol. uncertain; perhaps for 
 saracen stone , i.e., a heathen or pagan stone or monument.] One of the large sandstone blocks scattered over the English chalk downs; -- called also 
 sarsen stone , and 
 Druid stone . [ Eng.] 
Found on 
http://www.encyclo.co.uk/webster/S/18
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