Excellent advice to papa (6)
I believe the answer is:
tiptop
'excellent' is the definition.
(I've seen this before)
'advice to papa' is the wordplay.
'advice' becomes 'tip' (I've seen this before).
'papa' becomes 'p' (phonetic alphabet: alpha, bravo, charlie etc.).
'tip'+'to'+'p'='TIPTOP'
(Other definitions for tiptop that I've seen before include "Informally excellent, very best" , "First-class" , "The very highest point" , "Jolly good, excellent" , "Best of its kind" .)