Return of high temperature breaks my pool facing sudden pressure (2,3,4)
I believe the answer is:
on the spot
'return of high temperature breaks my pool facing sudden pressure' is the definition.
I can't judge whether this defines the answer.
'return of high temperature breaks my pool' is the wordplay.
'return of high temperature' becomes 'th' (I can't explain this - if you can you should believe this answer much more).
'breaks' means one lot of letters goes inside another (inserted letters break into the word).
'my' becomes 'one's' ('one's' is a humorous equivalent to 'my').
'pool' becomes 'pot' (both can mean the total stake in gambling).
'th' put inside 'ones' is 'onthes'.
'onthes'+'pot'='ON-THE-SPOT'
Can you help me to learn more?
(Other definitions for on the spot that I've seen before include "At the scene of the action" , "In a difficult position, forced to decide" , "Where cream may go" , "In a difficult situation?" , "sort of fine" .)