Static (8)
'static' is the definition.
(I've seen this before)
This is the entire clue.
(Other definitions for immobile that I've seen before include "Not able to move or be moved" , "Not capable of movement" , "Not going anywhere" , "stuck in the station, maybe" , "Incapable of motion" .)
(Other definitions for cling that I've seen before include "Hold on as for dear life" , "Adhere to - ring" , "Adhere, hold tight" , "fast" , "Hold tightly, become attached" .)