Shock for king in battle (6)
I believe the answer is:
fright
'shock' is the definition.
(I know that shock is a more specific form of the action alarm)
'king in battle' is the wordplay.
I cannot quite understand how this works, but
'king' could be 'r' (abbreviation for rex, king in Latin) and 'r' is located in the answer.
'battle' could be 'fight' (synonyms) and 'fight' is found within the remaining letters.
This accounts for all the letters.
This explanation may well be incorrect...
'for' acts as a link.
Can you help me to learn more?
(Other definitions for fright that I've seen before include "Panic" , "Grotesque" , "Shock, sudden alarm" , "Alarming event" , "Start" .)