All NHS leaders have duty to protect personnel from infectious disease (7)
I believe the answer is:
anthrax
'infectious disease' is the definition.
'anthrax' can be an answer for 'disease' (anthrax is a kind of disease). I also know that 'infectious' relates to this answer.
'all nhs leaders have duty to protect personnel' is the wordplay.
'leaders' suggests taking the first letters.
'have' means one lot of letters go next to another.
'duty' becomes 'tax' (I've seen this before).
'to protect' indicates putting letters inside.
'personnel' becomes 'hr' (Human Resources).
The initial letters of 'all nhs' is 'an'.
'tax' placed around 'hr' is 'thrax'.
'an'+'thrax'='ANTHRAX'
'from' acts as a link.
(Other definitions for anthrax that I've seen before include "Nasty illness" , "could ruin stock market" , "Highly infectious, sometimes deadly, disease of cattle" , "Animal disease" , "Disease of herbivores" .)