365 days with knight essentially seems scarily longer! (7)
I believe the answer is:
yearner
'longer' is the definition.
(I know that longer can be written as yearner)
'365 days with knight essentially seems scarily' is the wordplay.
'365 days' becomes 'year' (I've seen this before).
'with' says to put letters next to each other.
'knight' becomes 'N' (chess abbreviation).
'essentially' says to take the centre.
'scarily' becomes 'r' (I am not sure about this - if you are sure you should give a lot more credence to this answer).
The centre of 'seems' is 'e'.
'year'+'n'+'e'+'r'='YEARNER'
Can you help me to learn more?
(Other definitions for yearner that I've seen before include "discontented with his lot?" , "One longing" .)