I came across a puzzle about a missing letter in a primary school exercise booklet for selective high school exams in Australia. The puzzle is the one shown in the picture below. It looks like the missing letter is from a word of eight letters.
Another possibility, that uses the letters as arranged, instead of just being a straight anagram:
The missing letter is E.
Reading alternate letters clockwise you get TIME and TIDE.
(And for a bonus, reading anti-clockwise also works, giving EMIT and EDIT.)
This still isn't a very satisfactory answer because Y also works clockwise, giving TIDY.