Oscars presenter finally turned up, a little bounder (3)
I believe the answer is:
roo
'a little bounder' is the definition.
(I've seen this in another clue)
'oscars presenter finally turned up' is the wordplay.
'oscars' becomes 'OO' (two O's - Oscar is O in the phonetic alphabet).
'finally' suggests the final letters.
'turned up' is a reversal indicator.
The final letter of 'presenter' is 'r'.
'oo'+'r'='oor'
'oor' reversed gives 'ROO'.
(Other definitions for roo that I've seen before include "short jumper" , "young skipper" , "Kanga's child (Pooh)" , "Marsupial (dim.)" , "Kanga's child (Milne)" .)