Be ill, needing nurse round? The very last thing you want (4,3)
I believe the answer is:
tail end
'very last thing you want' is the definition.
I can't judge whether this definition defines the answer.
'be ill needing nurse round?' is the wordplay.
'be ill' becomes 'ail' (synonyms).
'needing nurse' becomes 'tend' (I am not sure about this - if you are sure you should believe this answer much more).
'round?' is an insertion indicator.
'ail' placed inside 'tend' is 'TAIL-END'.
'the' acts as a link.
Can you help me to learn more?
(Other definitions for tail end that I've seen before include "Back" , "Last batsmen" , "like late Charlie?" , "Final part" , "Hindmost part" .)