Mendicant wants something fried or boiled in pub (6)
I believe the answer is:
beggar
'mendicant' is the definition.
(synonyms)
'something fried or boiled in pub' is the wordplay.
'something fried or boiled' becomes 'egg' (eggs can be fried and boiled).
'in' indicates putting letters inside.
'pub' becomes 'bar' (both are drinking establishments).
'egg' put into 'bar' is 'BEGGAR'.
'wants' acts as a link.
(Other definitions for beggar that I've seen before include "I need bread" , "Person who can't choose?" , "vagrant" , "poor chap" , "Pauper or supplicant" .)