Bring up second seat (4)
I believe the answer is:
spew
'bring up' is the definition.
(thesaurus)
'second seat' is the wordplay.
'second' becomes 's' (common abbreviation).
'seat' becomes 'pew' (pew is a kind of seat).
's'+'pew'='SPEW'
(Other definitions for spew that I've seen before include "Fetch up" , "bring it up" , "issue" , "Gush forth, vomit" , "Casst out in a stream" .)