It may be of untold value (5,6)

'untold value' is the definition.
I don't know anything about this answer so I cannot judge whether this works.

'it may be of' is the wordplay.
I cannot quite see how this works, but
'it' could be 't' (abbreviation. e.g. in 'tis) and 't' is found in the answer.
'of' could be 'o' and 'o' is located in the answer.
This may be the basis of the clue (or it may be nonsense).

Can you help me to learn more?