Tiger Moth has to fly last bit of the journey (4,8)
I believe the answer is:
home straight
'last bit of the journey' is the definition.
I know nothing about this answer so I can't judge whether it can be defined by this definition.
'tiger moth has to fly' is the wordplay.
'to fly' is an anagram indicator.
'tiger'+'moth'+'has'='tigermothhas'
'tigermothhas' with letters rearranged gives 'HOME STRAIGHT'.
Can you help me to learn more?
(Other definitions for home straight that I've seen before include "Final stage of a racecourse" , "Last part of a race" , "final stage of race" , "Last stage of race" , "covered in neat report" .)