A great number of the apostles (4)
I believe the answer is:
heap
'a great number' is the definition.
(large number of things)
'of the apostles' is the wordplay.
'of' indicates a hidden word.
'HEAP' is hidden in the letters of 'the apostles'.
(Other definitions for heap that I've seen before include "Mound, pile" , "Mound - dilapidated vehicle" , "good deal" , "car on its last legs" , "Loose pile" .)