Heads banging on low bedroom ceilings? Those are frightful! (6,4,2,4,2,3,5)
I believe the answer is:
things that go bump in the night
'low bedroom ceilings? those are frightful' is the definition.
I don't know anything about this answer so I can't judge whether it can be defined by this definition.
'heads banging on' is the wordplay.
I cannot really understand how this works, but
'on' could be 'at' (I've seen this in other clues) and 'at' is found in the answer.
This explanation may well be incorrect...
Can you help me to learn more?