I can’t move: I have become sluggish (8)
I believe the answer is:
inactive
'sluggish' is the definition.
('inactive' can be similar in meaning to 'sluggish')
'i can't move i have' is the wordplay.
'move' is an anagram indicator.
'i have' becomes 'ive'.
'cant' is an anagram of 'nact'.
'i'+'nact'+'ive'='INACTIVE'
'become' acts as a link.
(Other definitions for inactive that I've seen before include "Not moving/working" , "Passive, not working or in motion" , "Passive or idle" , "Passive, doing nothing" , "Immobile, not working" .)