Stop one’s little boy going up on street (6)
I believe the answer is:
desist
'stop' is the definition.
(thesaurus)
'one's little boy going up on street' is the wordplay.
'one's' becomes 'is' (roman numeral**).
'little boy' becomes 'ed' (nickname or 'little' form of Edward).
'going up' is a reversal indicator.
'on street' becomes 'st' (I've seen this in other clues).
'is'+'ed'='ised'
'ised' backwards is 'desi'.
'desi'+'st'='DESIST'
(Other definitions for desist that I've seen before include "Whoa, cease" , "Cease; abstain" , "Leave off (doing a thing)" , "Stop (doing something)" , "'Refrain from, stop (6)'" .)