Lad hooligan sent up (3)
I believe the answer is:
boy
'lad' is the definition.
(I've seen this in another clue)
'hooligan sent up' is the wordplay.
'hooligan' becomes 'yob' (synonyms).
'sent up' is a reversal indicator.
'yob' written backwards gives 'BOY'.
(Other definitions for boy that I've seen before include "Youth" , "Male child" , "Young male" , "Lad" , "Young man" .)