Brown and green light — this takes two (5)
I believe the answer is:
tango
'this takes two' is the definition.
(as in the phrase 'it takes two to tango')
'brown and green light' is the wordplay.
'brown' becomes 'tan' (tan is a kind of brown).
'and' means one lot of letters go next to another.
'green light' becomes 'go' (I've seen this in other clues).
'tan'+'go'='TANGO'
(Other definitions for tango that I've seen before include "Movement from Argentina" , "Dance originating in Argentina" , "Latin-American dance - code for T" , "Dance of South American origin" , "Colourful dance from Argentina" .)