Buttonhole with a carnation initially added to price (6)
I believe the answer is:
accost
'buttonhole' is the definition.
(thesaurus)
'a carnation initially added to price' is the wordplay.
'initially' suggests taking the first letters.
'added to' means one lot of letters go next to another.
'price' becomes 'cost' ('cost' can be a synonym of 'price'**).
The initial letter of 'carnation' is 'c'.
'a'+'c'+'cost'='ACCOST'
'with' acts as a link.
(Other definitions for accost that I've seen before include "what solicitors do" , "Buttonhole" , "Approach boldly, solicit" , "Waylay" , "Approach and address (someone) aggressively" .)