Some render a service to remove marks (5)
I believe the answer is:
erase
'remove marks' is the definition.
(I've seen this in another clue)
'some render a service' is the wordplay.
'some' says the answer is hidden in the clue (some of the parts of the word are used).
'ERASE' can be found hidden inside 'render a service'.
'to' is the link.
(Other definitions for erase that I've seen before include "Eradicate" , "Blank out" , "Do away with" , "Remove, wipe out" , "Take out" .)