It checks on underground movement (11)
I believe the answer is:
seismograph
'it checks on underground' is the definition.
The definition suggests a singular noun which matches the answer.
'movement' is the wordplay.
I cannot really see how this works, but
'movement' could be 'rap' (rap is a kind of movement) and 'rap' is found in the answer.
This explanation may well be incorrect...
Can you help me to learn more?
(Other definitions for seismograph that I've seen before include "Instrument for registering earthquakes" , "Earthquake measuring instrument" , "Earthquake recorder" , "Earthquake detector" , "What detects such tremors" .)