Showed heads of department increasing shamelessness and messed around (9)
I believe the answer is:
displayed
'showed' is the definition.
(displaying is a kind of showing)
'heads of department increasing shamelessness and messed around' is the wordplay.
'heads of' indicates taking the first letters.
'and' means one lot of letters go next to another.
'messed around' becomes 'played'.
The initial letters of 'department increasing shamelessness' is 'dis'.
'dis'+'played'='DISPLAYED'
(Other definitions for displayed that I've seen before include "revealed" , "Shown publicly" , "Exhibited" , "Showed" , "show" .)