Shock from breaker's end in power cut ... (7)
I believe the answer is:
outrage
'shock' is the definition.
(synonyms)
'breaker's end in power cut' is the wordplay.
'end' suggests the final letters.
'in' is an insertion indicator.
'power cut' becomes 'outage' (an outage is a loss of power).
The final letter of 'breaker' is 'r'.
'r' put into 'outage' is 'OUTRAGE'.
'from' acts as a link.
(Other definitions for outrage that I've seen before include "furious reaction" , "A feeling of righteous anger" , "Profound indignation" , "Extreme indignation" , "Shock grossly" .)