Push for second search (5)
I believe the answer is:
shunt
'push' is the definition.
(thesaurus)
'second search' is the wordplay.
'second' becomes 's' (common abbreviation).
'search' becomes 'hunt' ('hunt' can be a synonym of 'search').
's'+'hunt'='SHUNT'
'for' is the link.
(Other definitions for shunt that I've seen before include "Rear end collision" , "Push, electrical conductor" , "Move wagons around" , "Transfer a train to another track" , "Move railway wagons etc" .)