Slugs for example live a short time (4)
I believe the answer is:
ammo
'slugs' is the definition.
(slug can informally mean bullet)
'live a short time' is the wordplay.
'live' becomes 'am' ('I live' means 'I am').
'a short time' becomes 'mo' (as in 'just a mo').
'am'+'mo'='AMMO'
'for example' acts as a link.
(Other definitions for ammo that I've seen before include "Bullets, shells (colloq.)" , "Shot" , "explosives, perhaps" , "Bullet" , "Bullets (sl.)" .)