Happen to collar servant producing evidence of injury (5,3)
I believe the answer is:
black eye
'injury' is the definition.
(black eye is a kind of injury)
'happen to collar servant producing evidence' is the wordplay.
I cannot really understand how this works, but
'servant' could be 'lackey' (lackey is a kind of servant) and 'lackey' is present in the answer.
'happen' could be 'be' and 'be' is present in the leftover letters.
This accounts for all the letters.
This may be the basis of clue (or it may be nonsense).
'of' is the link.
Can you help me to learn more?
(Other definitions for black eye that I've seen before include "Result of facial blow" , "Bruise on face" , "fight evidence" , "Visible sign of a fight" , "mouse" .)