Concerned and embarrassed about behind (7)
I believe the answer is:
related
'concerned' is the definition.
('relate' can be a synonym of 'concern')
'embarrassed about behind' is the wordplay.
'embarrassed' becomes 'red' (someone may blush or go red when embarrassed).
'about' means one lot of letters goes inside another.
'behind' becomes 'late' (as in behind schedule).
'red' placed around 'late' is 'RELATED'.
'and' is the link.
(Other definitions for related that I've seen before include "Having family links" , "Like family members" , "Akin, associated" , "Kin; connected" , "Connected by family ties" .)