Messed up with payroll, by and large (9)
I believe the answer is:
popularly
'by and large' is the definition.
Both the answer and definition are adverbs. Perhaps there's a link between them I don't understand?
'messed up with payroll' is the wordplay.
'messed' indicates an anagram (letters get messed up).
'with' is a charade indicator (letters next to each other).
'up'+'payroll'='uppayroll'
'uppayroll' with letters rearranged gives 'POPULARLY'.
Can you help me to learn more?
(Other definitions for popularly that I've seen before include "in way many people like" , "Usually" .)