Here's why:
* Long vowels have the same sound as the letter name (e.g., "a" in "ate", "e" in "me", "i" in "kite", "o" in "go", "u" in "cube").
* In "clover", the vowel "o" has a short vowel sound, as in "hot" or "lot".
Therefore, "clover" is a short vowel word.