Get into trouble when you cease to be an adherent (4,7)
I believe the answer is:
come unstuck
'get into trouble when you cease' is the definition.
I know nothing about this answer so I can't judge whether this works.
'be an adherent' is the wordplay.
'be' becomes 'come' (coming is a kind of being).
'an adherent' becomes 'unstuck' (I can't justify this - if you can you should give a lot more credence to this answer).
'come'+'unstuck'='COME UNSTUCK'
'to' acts as a link.
Can you help me to learn more?
(Other definitions for come unstuck that I've seen before include "Lose one's grip" , "Fail" , "detached?" , "experience a setback?" , "Suffer failure" .)