Insult nurse in conversation — that's fine for you? (2,4,6)
I believe the answer is:
up your street
Here is my best explanation:
'fine for you?' is the definition.
(something 'up your street' is of interest to you)
'insult nurse in conversation' is the wordplay.
'insult' becomes 'upyours' ('up yours' is an insult or vulgar reaction).
'nurse in conversation' becomes 'treet' (I can't explain this - if you can you should believe this answer much more).
'upyours'+'treet'='UP YOUR STREET'
'that's' acts as a link.