She's always short (3)
I believe the answer is:
eve
'she's' is the definition.
'always short' is the wordplay.
'always' becomes 'ever' ('ever' can be a synonym of 'always').
'short' means to remove the last letter.
'ever' with its last letter taken away is 'EVE'.
(Other definitions for eve that I've seen before include "Adam's partner" , "Period immediately before" , "Day before; first woman" , "First lady from the night before" , "See 13 Across" .)