Host right to wear tiny knickers (6)
I believe the answer is:
throng
'host' is the definition.
(both can mean a large group of people)
'right to wear tiny knickers' is the wordplay.
'right' becomes 'r' (abbreviation).
'to wear' means one lot of letters goes inside another (to wear something is to be covered up by it).
'tiny knickers' becomes 'thong' (skimpy underwear).
'r' put into 'thong' is 'THRONG'.
(Other definitions for throng that I've seen before include "Dense crowd" , "A great crowd of people" , "Densely packed crowd" , "Large densely-packed crowd" , "Large packed crowd" .)