Source : Webster's Revised Unabridged Dictionary (1913)

Clingstone \Cling"stone`\, a.
   Having the flesh attached closely to the stone, as in some
   kinds of peaches. -- n. A fruit, as a peach, whose flesh
   adheres to the stone.

Source : WordNet®

clingstone
     n : fruit (especially peach) whose flesh adheres strongly to the
         pit [syn: {cling}]