Meadow flower, originally, or part of one (4)
I believe the answer is:
leaf
'part of one' is the definition.
'leaf' can be an answer for 'part' (leaf is a kind of part). I'm not sure about the 'of one' bit.
'meadow flower originally' is the wordplay.
'meadow' becomes 'lea' (a lea is a grassy area).
'originally' says to take the initial letters.
The initial letter of 'flower' is 'f'.
'lea'+'f'='LEAF'
'or' acts as a link.
(Other definitions for leaf that I've seen before include "Foil" , "Tree part - page" , "Piece of foliage (to be turned over anew?)" , "Bit of tree, of book" , "Small part of wood" .)