Can, and must, build a holy hideaway! (7)
I believe the answer is:
sanctum
'a holy hideaway' is the definition.
'sanctum' can be an answer for 'hideaway' (thesaurus). I'm unsure of the 'a holy' bit.
'can and must build' is the wordplay.
'and' is a charade indicator (letters next to each other).
'build' is an anagram indicator.
'can' put after 'must' is 'mustcan'.
'mustcan' is an anagram of 'SANCTUM'.
Can you help me to learn more?
(Other definitions for sanctum that I've seen before include "A holy place, sometimes inner" , "Shrine" , "A person's private room, often inner" , "Room safe from disturbance" , "Place of total privacy" .)