First scuff on new boat shoe (5)
I believe the answer is:
sabot
'shoe' is the definition.
(I know that sabot is a type of shoe)
'first scuff on new boat' is the wordplay.
'first scuff' becomes 's' (1st letter of 'scuff').
'on' means one lot of letters goes inside another.
'new' is an anagram indicator.
'boat' with letters rearranged gives 'abot'.
's' put inside 'abot' is 'SABOT'.
(Other definitions for sabot that I've seen before include "sole support?" , "footwear from Paris" , "Boast about wooden shoe" , "French clog" , "This from last" .)