Harm poster, overturning iconic shot, removing head (6)
I believe the answer is:
damage
'harm' is the definition.
(synonyms)
I can't explain the rest of the clue.
Can you help me to learn more?
(Other definitions for damage that I've seen before include "Detrimental effect" , "Deface, harm" , "Ravages" , "Physical harm" , "Cost (slang)" .)