The most common and most likely answer to this crossword clue is the 9 letter word STRAINING
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More clues leading to the result STRAINING
Buddy explains!

The straight part
We know that "using a riddle" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case using a riddle = straining.The cryptic/wordplay part
In cryptic crossword there's often an wordplay/cryptic part as well.This part involves a more complex hint, such as an anagram, homophone, hidden word, etc.
Sadly, We don't have an explanation for this specific crossword clue yet.
What does STRAINING mean?
STRAINING verb- To hold tightly, to clasp.
- To apply a force or forces to by stretching out.
- To damage by drawing, stretching, or the exertion of force.
- To act upon, in any way, so as to cause change of form or volume, as when bending a beam.
- To exert or struggle (to do something), especially to stretch (one's senses, faculties etc.) beyond what is normal or comfortable.
- To stretch beyond its proper limit; to do violence to, in terms of intent or meaning.
- To separate solid from liquid by passing through a strainer or colander
- To percolate; to be filtered.
- To make uneasy or unnatural; to produce with apparent effort; to force; to constrain.
- To urge with importunity; to press.
- Hug somebody; to hold somebody tightly.
- To beget, generate (of light), engender, copulate (both of animals and humans), lie with, be born, come into the world.
- The act by which one strains. (muscles, etc)
- Filtering, the process of passing something through a strainer.