Simple couple coming across very sad (9)
I believe the answer is:
plaintive
'sad' is the definition.
(I've seen this in another clue)
'simple couple coming across very' is the wordplay.
'simple' becomes 'plain' (synonyms).
'couple' becomes 'tie' (I've seen this in another clue).
'coming across' means one lot of letters goes inside another.
'very' becomes 'v' (abbreviation).
'tie' enclosing 'v' is 'tive'.
'plain'+'tive'='PLAINTIVE'
(Other definitions for plaintive that I've seen before include "Wistful" , "Doleful" , "Maybe weeping" , "Pathetic" , "Sounding sad and mournful" .)