The term 'CERTAIN DEER' can be broken down into three crossword solutions: ROES, HART, and STAG. ROES are a species of deer native to Europe, Asia, and parts of North Africa. They are also known as the European Roe Deer or the Western Roe Deer. Harts are a species of deer native to Europe, Asia, and parts of North Africa. They are also known as the Red Deer or the European Red Deer. Stags are a species of deer native to Europe, Asia, and parts of North Africa. They are also known as the European Red Deer or the Red Deer. All three species of deer are considered to be certain deer.