All there is inside Morocco's mosques (6)
I believe the answer is:
cosmos
'all there is' is the definition.
(the universe, everything that exists)
'inside morocco's mosques' is the wordplay.
'inside' says the answer is hidden in the clue.
'COSMOS' can be found hidden inside 'moroccos mosques'.
(Other definitions for cosmos that I've seen before include "Universe as an ordered whole" , "Universe as an ordered system" , "The universe - a daisy" , "Universe seen as a whole" , "The universe, whole of creation" .)