Jack took plain Vada Paav piece finally (5)
I believe the answer is:
knave
'jack' is the definition.
(synonyms)
'took plain vada paav piece finally' is the wordplay.
'finally' indicates one should take the final letters.
The final letters of 'took plain vada paav piece' are 'KNAVE'.
(Other definitions for knave that I've seen before include "Rogue - card" , "Jack - the cad!" , "Dishonest man; jack" , "A rogue as in playing cards" , "pack member?" .)