State starts to revel in clothing (4)
I believe the answer is:
sari
'clothing' is the definition.
(sari is a kind of clothing)
'state starts to revel in' is the wordplay.
'state' becomes 'sai' (I am not sure about this - if you are sure you should believe this answer much more).
'starts to' suggests taking the first letters.
'in' indicates putting letters inside.
The initial letter of 'revel' is 'r'.
'sai' placed around 'r' is 'SARI'.
Can you help me to learn more?
(Other definitions for sari that I've seen before include "habit" , "Indian costume" , "Asian dress" , "Hindu woman's dress" , "South Asian garment (variant spelling)" .)