Tending to cause harm (11)
I believe the answer is:
detrimental
'tending to cause harm' is the definition.
(I've seen this before)
This is the entire clue.
(Other definitions for detrimental that I've seen before include "which is bad for one" , "not helpful" , "Harmful; admit, relent (anag.)" , "Causing harm" , "Tending to cause harm" .)