If going back home, it's for the best (6)
I believe the answer is:
finest
'for the best' is the definition.
(the most excellent or fine)
'if going back home' is the wordplay.
'going back' says the letters should be written backwards.
'home' becomes 'nest' (a bird's home).
'if' in reverse letter order is 'fi'.
'fi'+'nest'='FINEST'
'it's' is the link.
(Other definitions for finest that I've seen before include "Most exquisite" , "Superior in quality" , "Most delicate or topmost" , "Of the highest grade" , "Infest with the best" .)