Join stuck-up priest in bed every now and then (5)
I believe the answer is:
enter
'join' is the definition.
(I've seen this in other clues)
'up priest in bed every now and then' is the wordplay.
'up' says the letters should be written in reverse (in down clue: letters go upwards).
'every now and then' indicates alternate letters (letters selected at regular intervals).
'priest'+'in'+'bed'='priestinbed'
The alternate letters of 'priestinbed' are 'retne'.
'retne' in reverse letter order is 'ENTER'.
'stuck' is the link.
This may not be right. It may be part of another bit of the clue.
Can you help me to learn more?
(Other definitions for enter that I've seen before include "Come in - penetrate - record" , "Enrol" , "Enroll, sign up" , "Come/go in" , "Move into" .)