掛け釘 is read as かけくぎ (kakekugi) and means peg.
かけくぎ
kakekugi
かけじく
hanging scroll
かける
to apply (insurance)
かけ
credit
かかる
to (come) at
かけすて
fixed-term payment (usu. insurance)
かけざん
multiplication
かけきん
installment
かけごえ
shout (of encouragement, etc.)
かけもち
holding two or more positions concurrently
かけあい
dialogue
かけあう
to throw on each other