A number rule out showing charm (6)
I believe the answer is:
allure
'charm' is the definition.
(I've seen this before)
'a number rule out' is the wordplay.
'number' becomes 'l' (L is an example**).
'out' indicates anagramming the letters (out can mean wrong or inaccurate).
'rule' with letters rearranged gives 'lure'.
'a'+'l'+'lure'='ALLURE'
'showing' acts as a link.
(Other definitions for allure that I've seen before include "Charm, magnetism" , "There's glamour" , "Powerful attraction" , "Glamorous appeal" , "Attractiveness, glamour" .)