Now within reach of solving the riddle (7)
I believe the answer is:
charade
'riddle' is the definition.
(a charade is a puzzle or riddle)
'now within reach of solving' is the wordplay.
I cannot really understand how this works, but
'now' could be 'ad' (AD, Anno Domini, as opposed to BC, Before Christ) and 'ad' is found within the answer.
an anagram of 'reach' is 'chare' which is present in the left over letters.
This accounts for all the letters.
This may be the basis of the clue (or it may be nonsense).
'the' is the link.
Can you help me to learn more?
(Other definitions for charade that I've seen before include "An absurd pretence, or a guessing game" , "Acted riddle - pretence" , "Pretence - travesty" , "Farce - mime" , "Total pretence (as in game)" .)