Magnifying glass? Ring for delivery (5)

I haven't cracked this one yet — but the brilliant team at Times for the Times have:

Aural wordplay [for delivery]: LOUPE /  “Loop” (Ring).  A kind of small magnifier used by watchmakers or jewellers. I don’t know why there is a question mark as this appears to be a straight definiton and not by example. I didn’t know the word and was unable to get to it from wordplay so this was the clue responsible for my DNF.