False religion briefly embroiled in row about vision (6)
I believe the answer is:
ocular
'about vision' is the definition.
'false religion briefly embroiled in row' is the wordplay.
'false religion' becomes 'cult' (I've seen this before).
'briefly' means to remove the last letter.
'embroiled in' indicates putting letters inside.
'row' becomes 'oar' (I've seen this before).
'cult' with its final letter removed is 'cul'.
'cul' inserted into 'oar' is 'OCULAR'.
(Other definitions for ocular that I've seen before include "Connected with vision (med.)" , "Connected with the eyes or vision" , "Glaucoma's such" , "Of the eyes, visual" , "Of the eye - visible" .)