In a state of lassitude, take a rest (3)

I believe the answer is:
sit
'a rest' is the definition.
(I've seen this in other clues)
'in a state of lassitude' is the wordplay.
'SIT' is hidden within the letters.
However, I am not sure how the hidden word is indicated.
'take' is the link.
Can you help me to learn more?
(Other definitions for sit that I've seen before include "Take a chair" , "Rest on one's haunches" , "Perch" , "Model" , "as magistrates do" .)
