Raiment
Obi and Old Navy shirt are clothing items. They begin with the letter o.
I think it's 'ward'
Adage.
One anagram of all the letters in roast mules that a four-year-old child would recognize is:somersault
There is an old movie from 1914 that meets your requirements "Unjustly Accused"
raiment
There is one word and it is an old English word , it is slowh.
rags
age-old
ancient
raiment
young!
The letters unscramble into one modern word and one old English word:TwineWiten (Old English plural for "Wit")
Another word for an old horse in three letters that is not "nag" is "dam". A dam is what the mother horse is called.
old, orb
ancient
it could be grandad.