Number on both sides in small craft (7)
I believe the answer is:
sleight
'craft' is the definition.
(thesaurus)
'number on both sides in small' is the wordplay.
'number' becomes 'eight' (eight is a kind of number**).
'on' says to put letters next to each other.
'both sides in' suggests removing the centre (only the side letters remain).
'small' with its middle taken out is 'sl'.
'eight' after 'sl' is 'SLEIGHT'.
(Other definitions for sleight that I've seen before include "distraction?" , "Cunning action" , "craft" , "Dexterity (usually of hand)" , "Tricky cunning" .)