Also led astray by star for so long (6-3)
I believe the answer is:
toodle-pip
'for so long' is the definition.
(I've seen this before)
'also led astray by star' is the wordplay.
'also' becomes 'too' (synonyms).
'astray' indicates anagramming the letters.
'by' says to put letters next to each other.
'star' becomes 'pip' (star on a military uniform).
'led' anagrammed gives 'dle'.
'too'+'dle'+'pip'='TOODLE-PIP'
(Other definitions for toodle-pip that I've seen before include "Goodbye (dated)" , "Take care" , "Farewell (informal)" , "Farewell remark - dipole top (anag)" , "so long" .)