Final, desperate appeal for the most recent gas pressure reading (4-4)
I believe the answer is:
last-gasp
'final' is the definition.
'desperate appeal for the most recent gas pressure reading' is the wordplay.
I cannot quite understand how this works, but
'the' could be 't' (the is pronounced as a 't' sound in some dialects) and 't' is located in the answer.
an anagram of 'gas' is 'asg' which is present in the left over letters.
'pressure' could be 'p' (abbreviation) and 'p' is present in the answer.
The remaining letters 'las' is a valid word which might be clued in a way I don't understand.
This explanation may well be incorrect...
Can you help me to learn more?
(Other definitions for last-gasp that I've seen before include "Done in desperation at the final moment" , "Remnant of energy or final exhalation" , "Final breath or done at the last possible moment of effort" , "Final exhalation before death" , "Finalk expiration, moment of death" .)