Bungling agent means I'm upset, accepting end of dream (13)
I believe the answer is:
mismanagement
'bungling' is the definition.
(I've seen this before)
'agent means i'm upset accepting end of dream' is the wordplay.
'upset' indicates anagramming the letters.
'accepting' is an insertion indicator (inserted letters are accepted).
'end of' indicates one should take the final letters.
The last letter of 'dream' is 'm'.
'agent'+'means'+'im'='agentmeansim'
'agentmeansim' is an anagram of 'mismanageent'.
'mismanageent' placed around 'm' is 'MISMANAGEMENT'.
(Other definitions for mismanagement that I've seen before include "Poor running" , "Poor stewardship" , "Maladministration" , "Bad running (of company)" , "Bungling" .)