Charming way to secure Number One (5)
I believe the answer is:
sweet
'charming' is the definition.
(thesaurus)
'way to secure number one' is the wordplay.
'way' becomes 'st' (abbreviation for street).
'to secure' means one lot of letters goes inside another (inserted letters are secured inside).
'number one' becomes 'wee' (both can informally mean urinating).
'st' placed around 'wee' is 'SWEET'.
(Other definitions for sweet that I've seen before include "Sour companion" , "Kind" , "Tart, perhaps - or not tart" , "Dulcet - dessert" , "Ewes cycle it (anag) -- herb (myrrh)" .)