Current strength in the morning for every period of time (8)
I believe the answer is:
amperage
'current strength' is the definition.
(I've seen this before)
'morning for every period of time' is the wordplay.
'morning' becomes 'am'.
'for every' becomes 'per' ('per' means 'for each' or 'for every').
'period of time' becomes 'age' (age is a kind of period of time).
'am'+'per'+'age'='AMPERAGE'
'in the' acts as a link.
(Other definitions for amperage that I've seen before include "current measure" , "Strength of current" .)