Where oxygen and nitrogen are inhaled, coincidentally (2,3,4,6)
I believe the answer is:
in the same breath
'where' is the definition.
Both the definition and answer are adverbs. Maybe they are linked in a way I don't understand?
'oxygen and nitrogen are inhaled coincidentally' is the wordplay.
I cannot quite understand how this works, but
'and' could be 'n' (common abbreviation for 'and') and 'n' is present in the answer.
an anagram of 'are' is 'rea' which is within the answer.
This may be the basis of clue (or it may be nonsense).
Can you help me to learn more?
(Other definitions for in the same breath that I've seen before include "Together" , "with a single blow?" , "needing no further inspiration?" , "Without breaking off" .)