Strange people get a letter concerning a scrap (7)
I believe the answer is:
oddment
'a scrap' is the definition.
('oddment' can be a synonym of 'scrap')
'strange people get a letter' is the wordplay.
'strange' becomes 'odd' (I've seen this before).
'people' becomes 'men' (men are people).
'get' means one lot of letters go next to another.
'a letter' becomes 't' ().
'odd'+'men'+'t'='ODDMENT'
'concerning' is the link.
(Other definitions for oddment that I've seen before include "Remnant" , "Just a bit left" , "a bit spare" , "Scrap" , "Leftover piece" .)