Daughter coming in to mend broken bit (7)
I believe the answer is:
oddment
'bit' is the definition.
(I've seen this before)
'daughter coming in to mend broken' is the wordplay.
'daughter' becomes 'd'.
'coming in' means one lot of letters goes inside another.
'broken' is an anagram indicator.
'to'+'mend'='tomend'
'tomend' with letters rearranged gives 'odment'.
'd' going into 'odment' is 'ODDMENT'.
(Other definitions for oddment that I've seen before include "Remnant" , "An isolated article, something left over" , "Scrap" , "Piece left over, no match" , "Curiosity, peculiarity" .)