No end worried about them recovering (2,3,4)
I believe the answer is:
on the mend
'recovering' is the definition.
(I've seen this before)
'no end worried about them' is the wordplay.
'worried' indicates anagramming the letters.
'about' means one lot of letters goes inside another.
'no'+'end'='noend'
'noend' is an anagram of 'onend'.
'onend' placed around 'them' is 'ON THE MEND'.
(Other definitions for on the mend that I've seen before include "Recovering from an injury or illness" , "Regaining health" , "Informally getting better, improving after illness or accident" , "Improving in health" , "Looking up" .)