Harmful bloke if upset over money (10)
I believe the answer is:
maleficent
'harmful' is the definition.
(I've seen this before)
'bloke if upset over money' is the wordplay.
'bloke' becomes 'male'.
'upset' says the letters should be written in reverse.
'over money' becomes 'cent' (I've seen this before. I am not sure about the 'over' bit.).
'if' back-to-front is 'fi'.
'male'+'fi'+'cent'='MALEFICENT'
(Other definitions for maleficent that I've seen before include "Evil" , "Harmful" .)