Period of inactivity in rest, as I sit (6)
I believe the answer is:
stasis
'period of inactivity' is the definition.
(I've seen this before)
'in rest as i sit' is the wordplay.
'in' says the answer is hidden in the clue.
'STASIS' is hidden within 'rest as i sit'.
(Other definitions for stasis that I've seen before include "lack of action" , "Stoppage of blood circulation" , "Stoppage of blood flow in body" , "Stoppage, arrest" , "Stoppage of circulation or stagnation" .)