Visual operation leading to muscle problem (5)
I believe the answer is:
optic
'visual' is the definition.
(I know that visual can be written as optic)
'operation leading to muscle problem' is the wordplay.
'operation' becomes 'op'.
'leading to' says to put letters next to each other (some letters go before or lead others).
'muscle problem' becomes 'tic' (I've seen this in another clue).
'op'+'tic'='OPTIC'
(Other definitions for optic that I've seen before include "Of sight or the eye" , "Pertaining to sight" , "Teacher's maybe coming through this" , "Spirits dispenser" , "Relating to the eyes" .)