Survived being confined, losing oxygen (5)
I believe the answer is:
coped
'survived' is the definition.
'confined losing oxygen' is the wordplay.
'confined' becomes 'cooped'.
'losing' indicates named letters should be taken away.
'oxygen' becomes 'o' (atomic symbol for oxygen).
'cooped' with 'o' removed is 'COPED'.
'being' is the link.
(Other definitions for coped that I've seen before include "Managed, got by" , "Rose to the occasion" , "wearing vestment" , "as a priest in ceremony?" , "Made the grade" .)