Sauna made boiling until one was sick (2,7)
I believe the answer is:
ad nauseam
'until one was sick' is the definition.
(Latin phrase meaning 'to the point of nausea')
'sauna made boiling' is the wordplay.
'boiling' indicates an anagram.
'sauna'+'made'='saunamade'
'saunamade' is an anagram of 'AD NAUSEAM'.
(Other definitions for ad nauseam that I've seen before include "seasickness pills like this would be counterproductive?" , "Repeating" , "On and on - would make you sick" , "Interminably" , "Done so often that it becomes tiresome" .)