With child, having to inhale oxygen etc. (3,2,2)
I believe the answer is:
and so on
'etc' is the definition.
(I've seen this before)
'with child having to inhale oxygen' is the wordplay.
I cannot quite see how this works, but
'with' could be 'and' and 'and' is found in the answer.
'oxygen' could be 'o' (O is the chemical symbol for oxygen) and 'o' is located in the answer.
'child' could be 'son' (male child) and 'son' is located in the leftover letters.
This accounts for all the letters.
This may be the basis of the clue (or it may be nonsense).
Can you help me to learn more?
(Other definitions for and so on that I've seen before include "I say no more" , "Continuing in the same way" , "Et cetera" , "Etc. (3.2.2)" , "Etc - in English and in full" .)