Worried if aching, since husband's lost weight (12)
I believe the answer is:
significance
'weight' is the definition.
(I've seen this before)
'worried if aching since husband's lost' is the wordplay.
'worried' indicates anagramming the letters.
'husband' becomes 'h'.
'lost' indicates named letters should be taken away.
'if'+'aching'+'since'='ifachingsince'
'ifachingsince' with 'h' taken away is 'ifacingsince'.
'ifacingsince' with letters rearranged gives 'SIGNIFICANCE'.
(Other definitions for significance that I've seen before include "weight" , "Import" , "Importance, meaning" .)