Comrades run into monsters (7)
I believe the answer is:
friends
'comrades' is the definition.
(I've seen this before)
'run into monsters' is the wordplay.
'run' becomes 'r' (cricket abbreviation).
'into' means one lot of letters goes inside another.
'monsters' becomes 'fiends' ('fiend' can be a synonym of 'monster').
'r' going inside 'fiends' is 'FRIENDS'.
(Other definitions for friends that I've seen before include "playmates!" , "American sitcom" , "Intimate acquaintances" , "Buddies" , "Intimates" .)