Picked up shock in periods of global revolution (4)
I believe the answer is:
days
'periods of global revolution' is the definition.
(the Earth revolves once a day)
'picked up shock' is the wordplay.
'picked up' shows a homophone (sound like).
'shock' becomes 'daze' (synonyms).
'daze' sounds like 'DAYS'.
'in' is the link.
(Other definitions for days that I've seen before include "See 25" , "` `They are not long, the .... of wine and roses' ' (Dowson)" , "Twenty-four hour periods" , "Periods (of week)" , "See 7 and 18" .)