Mellow daughter solved clue on time (6)
I believe the answer is:
dulcet
'mellow' is the definition.
(thesaurus)
'daughter solved clue on time' is the wordplay.
'daughter' becomes 'd' (genealogical abbreviation).
'solved' indicates an anagram (the anagram must be solved).
'on' means one lot of letters goes inside another (as in clothing 'on' a person).
'time' becomes 't' (abbreviation).
'clue' anagrammed gives 'ulce'.
'd' inserted inside 'ulce' is 'dulce'.
'dulce'+'t'='DULCET'
(Other definitions for dulcet that I've seen before include "Sweet on the ear" , "Mellifluous, pleasant to the ear" , "Mellifluous, pleasing to the ear" , "Sweet - melodious" , "Soft, sweet (tones)" .)