Travel with wife, pay separately (2,5)
I believe the answer is:
go dutch
'pay separately' is the definition.
(I've seen this before)
'travel with wife' is the wordplay.
'travel' becomes 'go' (synonyms).
'with' means one lot of letters go next to another.
'wife' becomes 'dutch' (slang term).
'go'+'dutch'='GO DUTCH'
(Other definitions for go dutch that I've seen before include "Split the bill" , "Share costs equally" , "Share expenses - in Holland?" , "come to a fifty-fifty financial arrangement" , "Pay for one's own entertainment - in Holland?" .)