Pressure point, having ignored initial opening (8)
I believe the answer is:
puncture
This clue could be a double definition.
'pressure point' is the first definition.
'puncture' can be an answer for 'point' (thesaurus). I'm unsure of the 'pressure' bit.
'ignored initial opening' is the second definition.
'puncture' can be an answer for 'opening' (puncture is a kind of opening). I am unsure of the 'ignored initial' bit.
'having' is the link.
Can you help me to learn more?
(Other definitions for puncture that I've seen before include "Pierce (tyre etc)" , "Make a hole in" , "Tyre problem" , "reduce inflation quickly" , "Flat tyre" .)