In with her is that Jones character (5)
I believe the answer is:
diana
'in' is the definition.
Although both the answer and definition are singular nouns, I cannot see how they can define each other.
'her is that jones character' is the wordplay.
I cannot really understand how this works, but
'her' could be 'dian' and 'dian' is found within the answer.
'character' could be 'a' and 'a' is found within the answer.
This accounts for all the letters.
This explanation may well be incorrect...
'with' is the link.
Can you help me to learn more?
(Other definitions for diana that I've seen before include "Roman goddess of the hunt, or tragic English princess" , "Woman" , ""The People's Princess"" , "Roman goodess of hunting or tragic English princess" , "Roman godess of the hunt" .)