Right-o, darling! (4,4)
'darling' is the definition.
(thesaurus)
'right-o' is the wordplay.
'right' becomes 'true' ('true' is associated in meaning with 'right').
'o' becomes 'love' (I've seen this in other clues).
'true'+'love'='TRUELOVE'
(Other definitions for truelove that I've seen before include "'The course of ... ... ne'er ran smooth'" , "Quatrefoil" , "dearest" , "Sweetheart" , "'The course of ..... ne'er runs smooth'" .)
(Another definition for true love that I've seen is " Genuine affection?".)