Debate about working to cover case of asbestosis (6)
I believe the answer is:
reason
'debate' is the definition.
(thesaurus)
'about working to cover case of asbestosis' is the wordplay.
'about' becomes 're' (common abbreviation for 'with reference to').
'working' becomes 'on'.
'to cover' indicates putting letters inside.
'case of' suggests removing the centre (outsides of).
'asbestosis' with its centre removed is 'as'.
're'+'on'='reon'
'reon' going around 'as' is 'REASON'.
(Other definitions for reason that I've seen before include "Justification (for action)" , "Sanity, the ability to think" , "Mental power to justify an act" , "Capacity for rational thought" , "Motive for an action" .)