Harold has old ring (4)
I believe the answer is:
halo
'ring' is the definition.
(I know that ring can be written as halo)
'harold has old' is the wordplay.
'harold' becomes 'Hal' (diminutive, as in Hal Prince).
'has' says to put letters next to each other.
'old' becomes 'o' (abbreviation as in OT - Old Testament).
'hal'+'o'='HALO'
(Other definitions for halo that I've seen before include "Luminous sign of saintliness" , "Circle of light around the moon" , "Saint's circle of light" , "Symbol of sainthood" , "Hagiological aura featured in Christian art" .)