Prestigious award presented by no-mark? (5)
I believe the answer is:
oscar
'prestigious award' is the definition.
(I've seen this in another clue)
'by no-mark?' is the wordplay.
'by' is a charade indicator (letters next to each other).
'no' becomes 'O' (O resembles 0).
'mark?' becomes 'scar' (mark left by an injury).
'o' put next to 'scar' is 'OSCAR'.
'presented' is the link.
(Other definitions for oscar that I've seen before include "Cinema award" , "Phonetic code for O" , "Note" , "Film prize" , "US film award" .)