Extremely reliable eyesight needed for a change (8)
I believe the answer is:
revision
'a change' is the definition.
(revision is a kind of change)
'extremely reliable eyesight needed' is the wordplay.
'extremely' suggests removing the centre.
'eyesight' becomes 'vision' (I've seen this before).
'needed' says to put letters next to each other.
'reliable' with its middle taken out is 're'.
're'+'vision'='REVISION'
'for' acts as a link.
(Other definitions for revision that I've seen before include "requirement before exam" , "Action of amending and improving" , "Improving change" , "Cramming (for exam)" , "Studying - change" .)