Time, hours below, making loud noise (7)
I believe the answer is:
thunder
'loud noise' is the definition.
(I've seen this before)
'time hours below' is the wordplay.
'time' becomes 't' (abbreviation).
'hours' becomes 'h'.
'below' becomes 'under' (synonyms).
't'+'h'+'under'='THUNDER'
'making' acts as a link.
(Other definitions for thunder that I've seen before include "Noise heard after lightning" , "Speak in booming voice" , "It accompanies lightning" , "Boom; bellow" , "Meteorological rumblings" .)