Mature males on staff in film showing organisational incompetence (13)
I believe the answer is:
mismanagement
'organisational incompetence' is the definition.
(managing or organising things badly)
'mature males on staff in film' is the wordplay.
I cannot quite understand how this works, but
'mature' could be 'age' (synonyms) and 'age' is located in the answer.
'males' could be 'men' (man is a kind of male) and 'men' is found in the answer.
'staff' could be 'man' (as in staffing or manning a particular place) and 'man' is found in the answer.
'film' could be 'mist' (to film over is to mist or fog over) and 'mist' is found in the leftover letters.
This accounts for all the letters.
This explanation may well be incorrect...
'showing' is the link.
(Other definitions for mismanagement that I've seen before include "Poor running" , "Bungling" , "Bad running (of company)" , "Bad running (of something)" , "Bad handling" .)