Side by side, last of four snatched by a monster (7)
I believe the answer is:
abreast
'side by side' is the definition.
(synonyms)
I don't understand how the remainder of the clue works.
Can you help me to learn more?
(Other definitions for abreast that I've seen before include "Alongside one another and facing the same way" , "Level in line" , "Level or keeping pace with" , "On a level together" , "shoulder to shoulder" .)