Roman general marks margins with words opposite in meaning (8)
I believe the answer is:
antonyms
'words opposite in meaning' is the definition.
(I've seen this before)
'roman general marks margins' is the wordplay.
'roman general' becomes 'antony' (I've seen this before. I am not sure about the 'roman' bit.).
'margins' means to remove the middle letters (the letters on the margins are used).
'marks' with its middle taken out is 'ms'.
'antony'+'ms'='ANTONYMS'
'with' is the link.
Can you help me to learn more?
(Other definitions for antonyms that I've seen before include "Words opposite in meaning to others" , "They are opposed" , "Words with opposite meanings" , "'Good' and 'bad' are examples" , "My son, Nat, turns to words which are opposite in meaning" .)