Jack is disposed to do nothing in anger (6)
I believe the answer is:
ablaze
'in anger' is the definition.
(I've seen this before)
'jack is disposed to do nothing' is the wordplay.
I cannot really understand how this works, but
'jack' could be 'ab' (both can mean a sailor) and 'ab' is located in the answer.
'nothing' could be 'z' and 'z' is located in the answer.
This may be the basis of the clue (or it may be nonsense).
Can you help me to learn more?
(Other definitions for ablaze that I've seen before include "being toasted?" , "Fiery" , "filled with anger" , "Flaming; on fire" , "Bright" .)