Distinguish from satellite (4)
I believe the answer is:
tell
'distinguish' is the definition.
(I know that distinguish is a more specific form of mark)
'from satellite' is the wordplay.
'from' indicates a hidden word.
'TELL' is hidden within 'satellite'.
(Other definitions for tell that I've seen before include "work in a bank" , "Rossini composed opera 'William ....'" , "Count - recount" , "Peach" , "Grass - Swiss hero" .)