Sorrow engulfing Miles seen before knight's tomb (6)
I believe the answer is:
dolmen
'tomb' is the definition.
(I know that dolmen is a type of tomb)
'sorrow engulfing miles seen before knight's' is the wordplay.
'sorrow' becomes 'dole' (I am not sure about this - if you are sure you should give a lot more credence to this answer).
'engulfing' is an insertion indicator.
'miles' becomes 'm' (common abbreviation).
'seen before' says to put letters next to each other.
'knight' becomes 'N' (chess abbreviation).
'dole' placed around 'm' is 'dolme'.
'dolme'+'n'='DOLMEN'
Can you help me to learn more?
(Other definitions for dolmen that I've seen before include "Prehistoric megalithic tomb" , "Ancient tomb for old men" , "Type of megalithic tomb" , "ancient monument" .)