Head off to relax around start of parliamentary recess (4)
I believe the answer is:
apse
'recess' is the definition.
(apse is a kind of recess)
I don't understand how the rest of the clue works.
Can you help me to learn more?
(Other definitions for apse that I've seen before include "Part of a church with the altar" , "In sacred space" , "Church area" , "Offshoot from the choir, nave or aisle in a church" , "Recess at east end of church" .)