Small dispatch facility (5)
I believe the answer is:
skill
'facility' is the definition.
(I've seen this before)
'small dispatch' is the wordplay.
'small' becomes 's' (abbreviation - e.g. clothes size).
'dispatch' becomes 'kill' (I've seen this before).
's'+'kill'='SKILL'
(Other definitions for skill that I've seen before include "Knack" , "facility" , "Craft; dexterity" , "Aptitude" , "Ability - dexterity" .)