Staff generous, displaying humanity (7)
I believe the answer is:
mankind
'humanity' is the definition.
(I know that humanity can be written as mankind)
'staff generous' is the wordplay.
'staff' becomes 'man' (as in staffing or manning a particular place).
'generous' becomes 'kind' (similar in meaning).
'man'+'kind'='MANKIND'
'displaying' is the link.
(Other definitions for mankind that I've seen before include "Human race" , "all of us" , "people, in general" , "'One giant leap for - - '" , "Humanity" .)