Staff working to prop organisation, but not too much (2,3,6)
I believe the answer is:
ma non troppo
'but not too much' is the definition.
(I've seen this before)
'staff working to prop organisation' is the wordplay.
'staff' becomes 'man' (manning is a kind of staffing).
'working' becomes 'on'.
'organisation' is an anagram indicator.
'to'+'prop'='toprop'
'toprop' anagrammed gives 'troppo'.
'man'+'on'+'troppo'='MA NON TROPPO'
(Other definitions for ma non troppo that I've seen before include "musical direction" , "Not excessively" , "But not too much so (mus.)" .)