Former soldiers, for short (4)
I believe the answer is:
vets
'former soldiers for short' is the definition.
(I've seen this in another clue)
This is the entire clue.
(Other definitions for vets that I've seen before include "13 doctors?" , "Examines the animal doctors carefully?" , "Siegfried and Tristan Farnon, for example" , "Screens the animal doctors" , "Inspects (animals?)" .)