Wear down staff in telecommunications company (5)
I believe the answer is:
erode
'wear down' is the definition.
(to erode is to wear down or decay)
'staff in telecommunications company' is the wordplay.
'staff' becomes 'rod' (both can mean a stick or cane).
'in' indicates putting letters inside.
'telecommunications company' becomes 'ee' (I can't explain this - if you can you should believe this answer much more).
'rod' placed inside 'ee' is 'ERODE'.
Can you help me to learn more?
(Other definitions for erode that I've seen before include "Wear away with weather" , "'Deteriorate, wear away (5)'" , "Grind down" , "go to pieces!" , "Corrode" .)