Breathing apparatus hit tricky problem (8)
I believe the answer is:
blowhole
'breathing apparatus' is the definition.
The definition and answer can be both man-made objects as well as being singular nouns.
Maybe there's a link between them I don't understand?
'hit tricky problem' is the wordplay.
'hit' becomes 'blow' (blow can mean a hit).
'tricky problem' becomes 'hole' (I can't justify this - if you can you should give a lot more credence to this answer).
'blow'+'hole'='BLOWHOLE'
Can you help me to learn more?
(Other definitions for blowhole that I've seen before include "Whale's nostril" , "Opening for the escape of gas or air" , "Nostril of whale or dolphin on the top of its head" , "escape route from tunnel" .)