Cause to be valued by objective listener (6)
I believe the answer is:
endear
'cause to be valued' is the definition.
(to endear is to encourage affection)
'by objective listener' is the wordplay.
'by' says to put letters next to each other.
'objective' becomes 'end' (I've seen this before).
'listener' becomes 'ear' (I've seen this before).
'end' put next to 'ear' is 'ENDEAR'.
(Other definitions for endear that I've seen before include "Draw" , "Charm, captivate" , "Make love" , "Earned (anag.)" , "Evoke love - charm" .)