Harry Potter initially replanted trees (6)
I believe the answer is:
pester
'harry' is the definition.
(both can mean to bother)
'potter initially replanted trees' is the wordplay.
'initially' says to take the initial letters.
'replanted' indicates anagramming the letters (letters get placed or planted in new positions).
The initial letter of 'potter' is 'p'.
'trees' with letters rearranged gives 'ester'.
'p'+'ester'='PESTER'
(Other definitions for pester that I've seen before include "Trouble persistently" , "Bug" , "Annoy with frequent requests" , "Importune" , "Annoy with frequent questions" .)