Lack of movement in volcano — it can indeed erupt! (8)

I believe the answer is:

inaction

I'm a little stuck... Click here to teach me more about this clue!

'lack of movement' is the definition.
(I've seen this before)

I can't explain the remainder of the clue.

(Other definitions for inaction that I've seen before include "doing nothing whatsoever" , "Failure to exert oneself" , "Rest" , "Stasis" , "Idleness - fighting" .)

I've seen this clue in The Hindu.

Want a hint initially instead of a full solution? Install my app