Little Phillip also led astray before farewell (6-3)
I believe the answer is:
toodle-pip
'farewell' is the definition.
(I've seen this before)
'little phillip also led astray before' is the wordplay.
'little phillip' becomes 'pip' (Pip can be short for Philip. I am not sure about the 'little' bit.).
'also' becomes 'too' (synonyms).
'astray' indicates an anagram.
'before' means one lot of letters go next to another.
'led' with letters rearranged gives 'dle'.
'too'+'dle'='toodle'
'pip' put after 'toodle' is 'TOODLE-PIP'.
Can you help me to learn more?
(Other definitions for toodle-pip that I've seen before include "so long" , "Farewell (informal)" , "Take care" , "Farewell remark - dipole top (anag)" , "Goodbye (dated)" .)