Worry as to her range of hearing (7)
I believe the answer is:
earshot
'range of hearing' is the definition.
(I've seen this before)
'worry as to her' is the wordplay.
'worry' is an anagram indicator.
'as'+'to'+'her'='astoher'
'astoher' with letters rearranged gives 'EARSHOT'.
(Other definitions for earshot that I've seen before include "Extent of being heard" , "Range of audibility" , "To share (anag)" , "catching distance?" , "in audible range" .)