Starter in Rajasthan filling belly; boy, it's hot! (8)
I believe the answer is:
turmeric
'it's hot' is the definition.
(I've seen this before)
'starter in rajasthan filling belly boy' is the wordplay.
'starter in' suggests taking the first letters.
'filling' means one lot of letters goes inside another.
'belly' becomes 'tum' (I've seen this in another clue).
'boy' becomes 'eric' (I've seen this before).
The first letter of 'rajasthan' is 'r'.
'r' placed within 'tum' is 'turm'.
'turm'+'eric'='TURMERIC'
(Other definitions for turmeric that I've seen before include "Ingredient in curry powder" , "kitchen ingredient" , "Yellow spice used in curry" , "Yellow aromatic powder used in cooking" , "It's hot" .)