In suit, stitch up large dart (4)
I believe the answer is:
flit
'dart' is the definition.
(I know that dart can be written as flit)
'in suit stitch up large' is the wordplay.
I cannot quite understand how this works, but
'large' could be 'l' (eg in clothes sizes) and 'l' is located in the answer.
'suit' could be 'fit' (synonyms) and 'fit' is located in the remaining letters.
This accounts for all the letters.
This explanation may well be incorrect...
Can you help me to learn more?
(Other definitions for flit that I've seen before include "Run away (by moonlight?)" , "Scurry lightly" , "Fly quickly (by moonlight?)" , "Flutter - leave by moonlight?" , "Dart - elope" .)