Priest with no air has trouble breathing (11)
I believe the answer is:
respiration
'breathing' is the definition.
(I know that breathing can be written as respiration)
'priest with no air has trouble' is the wordplay.
I cannot really see how this works, but
'priest' could be 'p' (ecclesiastical abbreviation) and 'p' is located in the answer.
'no' could be 'o' (O resembles 0) and 'o' is located in the answer.
an anagram of 'air' is 'ira' which is present in the answer.
The remaining letters 'restin' is a valid word which might be clued in a way I don't see.
This explanation may well be incorrect...
Can you help me to learn more?
(Other definitions for respiration that I've seen before include "Breathing" , "See 1" .)