Fitted with small pipes over the opening (5)
I believe the answer is:
debut
'the opening' is the definition.
(I've seen this before)
I can't explain the remainder of the clue.
Can you help me to learn more?
(Other definitions for debut that I've seen before include "First appearance in society" , "First appearance, coming out" , "Start -- launch" , "The coming out of a society girl" , "Aurora" .)