Mass or short prayer (7)
I believe the answer is:
collect
This clue is a double definition.
'mass' is the first definition.
(I've seen this before)
'short prayer' is the second definition.
(I've seen this before)
'or' is the link.
(Other definitions for collect that I've seen before include "How people in America may be called" , "Gather; pick up" , "Fetch" , "Amass; a prayer" , "Gather together, for a short prayer perhaps" .)