Light dress on the other side of the street (6)
I believe the answer is:
strobe
'light' is the definition.
(strobe light is a type of light)
'dress on the other side of the street' is the wordplay.
'dress' becomes 'robe' (robing is a kind of dressing).
'on' means one lot of letters go next to another.
'the other' indicates an anagram.
'side of' suggests taking the first letters (the letter from one side of the word).
The initial letters of 'the street' is 'ts'.
'ts' anagrammed gives 'st'.
'robe' put after 'st' is 'STROBE'.
(Other definitions for strobe that I've seen before include "Protestant reformer" , "High-intensity flashing beam of light" , "Sorbet (anag) -flashing light" , "Flash on and off" , "Flashing lamp" .)