Heard couple as well (3)
I believe the answer is:
too
'as well' is the definition.
(both can mean 'also')
'heard couple' is the wordplay.
'heard' indicates a 'sounds like' (homophone) clue.
'couple' becomes 'two' (two people or things).
'two' is a homophone of 'TOO'.
(Other definitions for too that I've seen before include "To a greater than desirable extent" , "Excessively" , "Unduly" , "Likewise" , "Furthermore" .)