Entrance with fix, but it's comparatively dead (8)
I believe the answer is:
doornail
'it's comparatively dead' is the definition.
I can't tell whether this definition defines the answer.
'entrance with fix' is the wordplay.
'entrance' becomes 'door' (door is a kind of entrance).
'with' means one lot of letters go next to another.
'fix' becomes 'nail' (I've seen this before).
'door'+'nail'='DOORNAIL'
'but' is the link.
Can you help me to learn more?
(Other definitions for doornail that I've seen before include "Dead as a ...-very dead indeed" , "Dead as a ........ is dead without a doubt" , "popularly believed dead" , "proverbially dead" , "Stud" .)