Perforate pan, but not at first (6)
I believe the answer is:
riddle
'perforate' is the definition.
(I've seen this in another clue)
I can't explain the remainder of the clue.
Can you help me to learn more?
(Other definitions for riddle that I've seen before include "Sphinx's conundrum?" , "it's full of holes" , "Eg, When is a door not a door?" , "unsolved problem" , "Word puzzle or coarse sieve" .)