A month in the same place by English lake - a sound measure (7)
I believe the answer is:
decibel
'a sound measure' is the definition.
(I've seen this before)
'a month in the same place by english lake' is the wordplay.
'a month' becomes 'Dec' (abbreviation for December).
'in the same place' becomes 'ib' (short for ibid, in the previously cited source).
'by' is a charade indicator (letters next to each other).
'english' becomes 'E' (abbreviation).
'lake' becomes 'L' (geographical abbreviation).
'dec'+'ib'+'e'+'l'='DECIBEL'
(Other definitions for decibel that I've seen before include "Unit of measurement for loudness" , "I relate to volume" , "Unit for measuring intensity of sound" , "Noise unit" , "Measure of sound" .)