Shout for second best (6)
I believe the answer is:
scream
'shout' is the definition.
(I know that shout can be written as scream)
'second best' is the wordplay.
'second' becomes 's' (common abbreviation).
'best' becomes 'cream' (as in 'the cream of the crop').
's'+'cream'='SCREAM'
'for' acts as a link.
(Other definitions for scream that I've seen before include "irresistibly funny person" , "Funny person; cry" , "A shrill yell as from fright" , "'Loud, high-pitched cry (6)'" , "Caution" .)