Frank trailing in last part of the race (4,8)
I believe the answer is:
home straight
'last part of the race' is the definition.
I know nothing about this answer so I cannot judge whether this works.
'frank trailing in' is the wordplay.
'frank' becomes 'straight' (I've seen this before).
'trailing' means one lot of letters go next to another.
'in' becomes 'home' ('he's in' can mean 'he's home').
'straight' put after 'home' is 'HOME STRAIGHT'.
Can you help me to learn more?
(Other definitions for home straight that I've seen before include "Last stage of race" , "Final stage of a racecourse" , "final stage of race" , "Last part of a race" , "covered in neat report" .)