See you pocketing one crown (5)
I believe the answer is:
tiara
'crown' is the definition.
(tiara is a type of crown)
'see you pocketing one' is the wordplay.
'see you' becomes 'ta-ra' (both can mean goodbye).
'pocketing' means one lot of letters goes inside another (pocket can mean to steal or take possession of).
'one' becomes 'i' (Roman numeral).
'tara' enclosing 'i' is 'TIARA'.
(Other definitions for tiara that I've seen before include "Ornamental head gear" , "Jewelled hair-band" , "Jewelled coronet" , "Jewelled headpiece" , "Small crown" .)