A witty companion, this charmer? (5)
I believe the answer is:
witch
'this charmer?' is the definition.
(someone who charms)
'a witty companion' is the wordplay.
'a witty' becomes 'wit' (I can't justify this - if you can you should believe this answer much more).
'companion' becomes 'ch' (Companion of Honour).
'wit'+'ch'='WITCH'
Can you help me to learn more?
(Other definitions for witch that I've seen before include "One of a coven" , "Female member of coven" , "Broomstick riderof children's tales" , "Wise, wicked, woman" , "Sorceress" .)