Apparently a prayer to make a man sit up! (6)
I believe the answer is:
mantis
'apparently a prayer to' is the definition.
I can't judge whether this defines the answer.
'a man sit up' is the wordplay.
'up' is a reversal indicator (in down clue: letters go upwards).
'sit' written backwards gives 'tis'.
'man'+'tis'='MANTIS'
'make' is the link.
Can you help me to learn more?
(Other definitions for mantis that I've seen before include "Large-eyed insect, looks as if it's praying" , "Praying insect at matins" , "Room equipped for milking cows" , "Preying animal, the female of which is deadlier than the male!" , "Insect with limbs raised as if in prayer" .)