Old man presented with extremely pretty flower (5)
I believe the answer is:
poppy
'flower' is the definition.
(I know that poppy is a type of flower)
'old man presented with extremely pretty' is the wordplay.
'old man' becomes 'pop' (both can mean one's father).
'presented with' says to put letters next to each other.
'extremely' means to remove the middle letters (only the extremes of the word are used).
'pretty' with its middle removed is 'py'.
'pop'+'py'='POPPY'
(Other definitions for poppy that I've seen before include "Girl's name -- scarlet flower" , "Cornfield plant" , "catchy records like this" , "Bright red flower, source of opium" , "Wild flower having its day in November" .)