It's best if returning home (6)
I believe the answer is:
finest
'it's best' is the definition.
(the most excellent or fine)
'if returning home' is the wordplay.
'returning' says the letters should be written in reverse.
'home' becomes 'nest' (a bird's home).
'if' backwards is 'fi'.
'fi'+'nest'='FINEST'
(Other definitions for finest that I've seen before include "Infest with the best" , "A1" , "Of the highest quality" , "Most splendid" , "Of the highest grade" .)