Mark, in a strange way, the top (5)
I believe the answer is:
stain
'mark' is the definition.
(I know that mark can be written as stain)
'in a strange way the top' is the wordplay.
I cannot quite see how this works, but
'in' is within the answer.
'a' is within the answer.
'way' could be 'st' (abbreviation for street) and 'st' is found in the answer.
No letters remain.
This explanation may well be incorrect...
Can you help me to learn more?
(Other definitions for stain that I've seen before include "Black mark for saint" , "Dirty mark; dye" , "Discolouring mark" , "Colour, dye" , "Discoloured mark" .)