Equipment that can always let you down (9)
I believe the answer is:
parachute
This clue could be a double definition.
'equipment that can always let you' is the first definition.
'parachute' can be an answer for 'equipment' (parachute is a kind of equipment). I am unsure of the remainder of the definition.
'down' is the second definition.
(thesaurus)
Can you help me to learn more?
(Other definitions for parachute that I've seen before include "Eat up char for something to break your fall" , "Equipment for making a descent from an airplane" , "canopy" , "It breaks a fall from the sky" , "Devise for making descent from an airplane" .)