Marksman is late - first person is overheard (7)
I believe the answer is:
deadeye
'marksman' is the definition.
(I know that deadeye is a type of crack shot)
'late first person is overheard' is the wordplay.
'late' becomes 'dead' (similar in meaning).
'first person' becomes 'I' (first-person pronoun).
'is overheard' shows a homophone (sound like) (I've seen 'were overheard' mean this).
'i' sounds like 'eye'.
'dead'+'eye'='DEADEYE'
'is' is the link.
(Other definitions for deadeye that I've seen before include "Crack shot" , "One secures a shroud" , "top marksman" , "Dick" , "Ace marksman" .)