Prince Henry has a ring, a ring of saintliness (4)
I believe the answer is:
halo
'a ring of saintliness' is the definition.
(I've seen this before)
'prince henry has a ring' is the wordplay.
I cannot really see how this works, but
'prince' could be 'hal' (name for Prince Henry in Shakespeare's histories) and 'hal' is found within the answer.
'ring' could be 'o' (letter resembling a ring) and 'o' is present in the answer.
This accounts for all the letters.
This may be the basis of the clue (or it may be nonsense).
Can you help me to learn more?
(Other definitions for halo that I've seen before include "Luminous sign of saintliness" , "Imaginary circle over saint's head" , "glory" , "Saint's headlight?" , "Ring round head of saint" .)