Denis touring Australia with a group (5)
I believe the answer is:
dozen
'a group' is the definition.
Although both the answer and definition are singular nouns, I cannot see how they can define each other.
'denis touring australia' is the wordplay.
'denis' becomes 'den' (I can't explain this - if you can you should believe this answer much more).
'touring' indicates putting letters inside (touring can mean going round).
'australia' becomes 'oz' (informal name for Australia).
'den' enclosing 'oz' is 'DOZEN'.
'with' is the link.
Can you help me to learn more?
(Other definitions for dozen that I've seen before include "Set of twelve" , "A number of disciples" , "Twelfth of a gross" , "A small number" , "Group of 12" .)