Love is an entry for a sound relationship (5)
I believe the answer is:
adore
'love' is the definition.
(adoring is a kind of loving)
'an entry for a sound relationship' is the wordplay.
'entry' says to take the initial letters.
'for' is a charade indicator (letters next to each other).
'a sound relationship' becomes 'dore' (I can't justify this - if you can you should believe this answer much more).
The first letter of 'an' is 'a'.
'a'+'dore'='ADORE'
'is' acts as a link.
Can you help me to learn more?
(Other definitions for adore that I've seen before include "Worship, venerate" , "Treasure" , "Worship and glorify" , "Very much like" , "Love, revere intensely" .)