Vibration from rocky peak restricting sleep (6)
I believe the answer is:
tremor
'vibration' is the definition.
(I know that tremor is a type of vibration)
'rocky peak restricting sleep' is the wordplay.
'rocky peak' becomes 'tor' (a tor is a rocky hill).
'restricting' is an insertion indicator.
'sleep' becomes 'rem' (abbreviation for Rapid Eye Movement).
'tor' going around 'rem' is 'TREMOR'.
'from' is the link.
(Other definitions for tremor that I've seen before include "Small vibration" , "A slight shake, body or earth" , "Bit of excitement" , "Minor quake" , "Involuntary shudder" .)