Range of hearing aids originally despatched (4)
I believe the answer is:
ural
'range' is the definition.
(I've seen this in other clues)
'of hearing aids originally despatched' is the wordplay.
'of hearing aids' becomes 'aural'.
'originally despatched' means to remove the first letter (the original letter is sent away).
'aural' with its initial letter removed is 'URAL'.
(Other definitions for ural that I've seen before include "The - mountains separate Asia and Europe" , "River of central Russia" , "Asian flower" , "Russian river giving name to mountain range" , "Mountain range between Europe and Asia" .)