Ode old man composed forecasting disaster (4-5)
I believe the answer is:
doom-laden
'forecasting disaster' is the definition.
(I've seen this before)
'ode old man composed' is the wordplay.
'composed' indicates anagramming the letters.
'ode'+'old'+'man'='odeoldman'
'odeoldman' with letters rearranged gives 'DOOM-LADEN'.
(Other definitions for doom-laden that I've seen before include "apt to cause grief?" , "Conveying disaster" , "Gloomy" , "Forecasting disaster" .)