Incompetent type, one blowing something out of proportion, ultimately (7)
I believe the answer is:
bungler
'incompetent type' is the definition.
(I know that bungler are bumbling)
'one blowing something out of proportion ultimately' is the wordplay.
I cannot really see how this works, but
'one' could be 'un' (northern English dialect form of 'one') and 'un' is found within 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 bungler that I've seen before include "One prone to error" , "Clumsy incompetent" , "Clumsy executant" , "Someone prone to getting it wrong" .)