Top bird holding a presentation (8)
I believe the answer is:
bestowal
'presentation' is the definition.
(I've seen this before)
'top bird holding a' is the wordplay.
'top' becomes 'best' (associated in meaning).
'bird' becomes 'owl' (owl is a kind of bird).
'holding' means one lot of letters goes inside another.
'owl' placed around 'a' is 'owal'.
'best'+'owal'='BESTOWAL'
(Other definitions for bestowal that I've seen before include "Act of conferring (eg, grant on someone)" , "presentation" , "award" , "Act of giving" , "Conferment (of an honour)" .)