Smear second-rate group (4)
I believe the answer is:
blot
'smear' is the definition.
(I know that smear can be written as blot)
'second-rate group' is the wordplay.
'second-rate' becomes 'b' (second grade after A).
'group' becomes 'lot'.
'b'+'lot'='BLOT'
(Other definitions for blot that I've seen before include "Dark mark or stain" , "Cross out; inky mess" , "Don't do it to your copybook" , "Smudge of ink" , "Stain left by spilled ink" .)