Sluggish or random movement over time (7)
I believe the answer is:
dormant
'sluggish' is the definition.
(I've seen this before)
'random movement over time' is the wordplay.
'movement' indicates an anagram (letters move around).
'over' means one lot of letters go next to another.
'time' becomes 't' (abbreviation).
'random' with letters rearranged gives 'dorman'.
'dorman'+'t'='DORMANT'
'or' acts as a link.
(Other definitions for dormant that I've seen before include "Hibernating" , "Comatose" , "Lethargic" , "Lying inactive as if in sleep" , "Temporarily quiet" .)