Mark and Mike in unconscious state (5)
I believe the answer is:
comma
'mark' is the definition.
(punctuation mark)
'mike in unconscious state' is the wordplay.
'mike' becomes 'M' (phonetic alphabet: alpha, bravo, charlie etc.).
'in' indicates putting letters inside.
'unconscious state' becomes 'coma' (I've seen this in another clue).
'm' going inside 'coma' is 'COMMA'.
'and' acts as a link.
(Other definitions for comma that I've seen before include "Punctuation mark - butterfly" , "Mark for smallest division of a sentence" , "Brief stop" , "Kind of butterfly" , "Common punctuation park" .)