Sound coming from furrow on the level (5)
I believe the answer is:
pukka
'on the level' is the definition.
(both can mean legitimate)
'sound coming from furrow' is the wordplay.
'sound coming from' shows a homophone (sound like).
'furrow' becomes 'pucker' (as in furrowing or puckering one's face).
'pucker' is a homophone of 'PUKKA'.
(Other definitions for pukka that I've seen before include "that's for sure" , "not mock" , "Rightful" , "Bona fide" , "Genuine; reliable" .)