Extremely tough work environment causing various ailments (4,4)
I believe the answer is:
salt mine
'extremely tough work environment' is the definition.
'various ailments' is the wordplay.
'various' is an anagram indicator.
'ailments' anagrammed gives 'SALT-MINE'.
'causing' is the link.
(Other definitions for salt mine that I've seen before include "Deep pit containing a white substance" , "Ailments (anag)" , "Excavation" , "Source of flavouring" .)