Beg mischief-maker to take on new role (7)
I believe the answer is:
implore
'beg' is the definition.
(synonyms)
'mischief-maker to take on new role' is the wordplay.
'mischief maker' becomes 'imp' (I've seen this in other clues).
'to take on' says to put letters next to each other.
'new' is an anagram indicator.
'role' with letters rearranged gives 'lore'.
'imp'+'lore'='IMPLORE'
(Other definitions for implore that I've seen before include "Beg earnestly, beseech" , "More lip (anag)" , "Beg desperately" , "Ask earnestly" , "Beg earnestly, plead" .)