Greatly disturbed about husband's listlessness (8)
I believe the answer is:
lethargy
'listlessness' is the definition.
(thesaurus)
'greatly disturbed about husband's' is the wordplay.
'disturbed' indicates an anagram.
'about' indicates putting letters inside.
'husband' becomes 'h'.
'greatly' with letters rearranged gives 'letargy'.
'letargy' enclosing 'h' is 'LETHARGY'.
(Other definitions for lethargy that I've seen before include "Extreme lack of energy, listlessness" , "Drowsy" , "Torpor" , "Being sluggish" , "'Lassitude, langour (8)'" .)