Possible Clues:

• "...that he may --- you as wheat" (Luke 22:31)
• Distinguish as with a riddle
• Examine closely, as evidence
• Sieve, examine closely
• Search if found in street
• Sort (out)
• In a way, provided riddle
• Free of coarseness, in a way
• Remove lumps from, eg, flour
• Pan for gold, say