Visual adjustment subject to forcible separation (8)
I believe the answer is:
avulsion
'separation' is the definition.
(I know that avulsion is a type of separation)
'visual adjustment subject to forcible' is the wordplay.
I cannot quite see how this works, but
an anagram of 'visual' is 'avulsi' which is present in the answer.
'subject to' could be 'on' (I've seen this in other clues) and 'on' is found in the answer.
No letters remain.
This may be the basis of the clue (or it may be nonsense).
Can you help me to learn more?
(Another definition for avulsion that I've seen is " separation".)