I can’t move: I have become sluggish (8)
I believe the answer is:
Here is my best explanation:
'sluggish' is the definition.
('inactive' can be similar in meaning to 'sluggish')
'i cant move i have' is the subsidiary indication.
'move' is an anagram indicator.
'i have' becomes 'ive'.
'cant' with letters rearranged gives 'nact'.
'become' is the link.
(Other definitions for inactive that I've seen before include "Immobile, not working", "Passive, doing nothing", "Resting", "Quiescent", "Not moving/working", "Lifeless", "Having no effect", "Lethargic", "Unoccupied" and "sluggish".)