Emptied small cube showing dexterity (7)
I believe the answer is:
sleight
'dexterity' is the definition.
('sleight' can be a synonym of 'dexterity')
'emptied small cube' is the wordplay.
'emptied' suggests removing the centre.
'cube' becomes 'eight' (8 is a cube number).
'small' with its centre taken out is 'sl'.
'sl'+'eight'='SLEIGHT'
'showing' is the link.
(Other definitions for sleight that I've seen before include "distraction?" , "It's deceiving to the eye" , "Dexterity (usually of hand)" , "Manual dexterity" , "Cunning action" .)