On top of everything else, dispatcher loses script (4)
I believe the answer is:
head
'on top' is the definition.
'head' can be an answer for 'top' (synonyms). I am unsure of the 'on' bit.
I can't explain the rest of the clue.
Can you help me to learn more?
(Other definitions for head that I've seen before include "Chief; go first" , "Chief; promontory" , "Leader; stream source" , "Skull" , "Beer foam; front" .)