Right to go in a light dress (5)
I believe the answer is:
array
'dress' is the definition.
(I've seen this before)
'right to go in a light' is the wordplay.
'right' becomes 'r' (common abbreviation).
'to go in' is an insertion indicator.
'light' becomes 'ray' (ray is a kind of light).
'a'+'ray'='aray'
'r' inserted within 'aray' is 'ARRAY'.
(Other definitions for array that I've seen before include "Impressive exhibition" , "Significant arrangement" , "Imposing assembly" , "Orderly arrangement" , "Deck" .)