Degree of rage depends on possibility of suffering injury (6)
I believe the answer is:
danger
'possibility of suffering injury' is the definition.
'danger' can be an answer for 'possibility' (I have seen 'Undesirable possibility' mean 'danger' so perhaps 'possibility' could also mean 'danger'). I'm not certain of the 'of suffering injury' bit.
'degree of rage depends' is the wordplay.
I cannot quite see how this works, but
'degree' could be 'an' (AN is an example) and 'an' is found in the answer.
This explanation may well be incorrect...
'on' is the link.
Can you help me to learn more?
(Other definitions for danger that I've seen before include "Ranged about in some peril" , "Peril in garde" , "Peril, jeopardy" , "Peril, hazard" , "Peril, threat" .)