Favourite name for a flower part (5)
I believe the answer is:
petal
'for a flower part' is the definition.
(I've seen this in another clue)
'favourite name' is the wordplay.
'favourite' becomes 'pet' (synonyms).
'name' becomes 'al' ().
'pet'+'al'='PETAL'
(Other definitions for petal that I've seen before include "Floral leaf" , "Leaf-like part of flower head" , "part taken from stock?" , "Bloom's part" , "Part of a flowers corolla" .)