Nothing blocks machine, all wrecked, attaining the dumps (11)
I believe the answer is:
'the dumps' is the definition.
(both can mean moodiness or sadness)
'nothing blocks machine all wrecked' is the wordplay.
'nothing' becomes 'O' (looks like zero - 0).
'blocks' means one lot of letters goes inside another (the inside letters form a 'blockage').
'wrecked' indicates anagramming the letters.
'machineall' anagrammed gives 'melanchlia'.
'o' put inside 'melanchlia' is 'MELANCHOLIA'.
'attaining' is the link.
(Other definitions for melancholia that I've seen before include "Black dog" , "Depressed state" , "Feeling of deep sadness" , "Pensive sadness" , "Deep long-lasting sadness" .)