Key change (5)
I believe the answer is:
shift
I believe this clue is a double definition.
'key' is the first definition.
(key on a computer keyboard)
'change' is the second definition.
(shifting is a kind of changing)
(Other definitions for shift that I've seen before include "Simple dress; spell of work" , "Dislodge" , "Alter" , "Change (gear); dress" , "Move; straight dress" .)