Go astray during peak in awful mental state (6)
I believe the answer is:
terror
'mental state' is the definition.
(I know that terror is a type of mental state)
'go astray during peak' is the wordplay.
'go astray' becomes 'err' (to err is to make an error or go the wrong way).
'during' indicates putting letters inside.
'peak' becomes 'tor' (a tor is a rocky peak).
'err' inserted into 'tor' is 'TERROR'.
'in awful' acts as a link.
I am not very happy about this link. Some or all of it may belong to another bit of the clue.
Can you help me to learn more?
(Other definitions for terror that I've seen before include "Extreme fright or dread" , "rogue" , "Alarm" , "Abject fear" , "Organised political violence" .)