A member removed from the regular Marines (3)
I believe the answer is:
arm
'a member' is the definition.
(member can mean a limb)
'removed from the regular marines' is the wordplay.
'removed from' indicates the answer is hidden within the clue.
'ARM' can be found hidden inside 'regular marines'.
(Other definitions for arm that I've seen before include "Body part" , "Activate fuse" , "Division of company" , "Upper limb" , "Authority" .)