One with retina trouble - no movement (7)
I believe the answer is:
inertia
'no movement' is the definition.
The definition and answer can be both types of natural phenomena as well as being singular nouns.
Perhaps they are linked in a way I don't understand?
'one with retina trouble' is the wordplay.
'one' becomes 'i' (Roman numeral).
'with' is a charade indicator (letters next to each other).
'trouble' is an anagram indicator.
'retina' is an anagram of 'nertia'.
'i'+'nertia'='INERTIA'
Can you help me to learn more?
(Other definitions for inertia that I've seen before include "Passiveness" , "Display laziness" , "lack of action" , "Lack of activity" , "Motion (if any) when no external force is applied" .)