Romeo’s lass cut top off plant (7)
I believe the answer is:
gallant
'romeo's' is the definition.
(thesaurus)
'lass cut top off plant' is the wordplay.
'lass' becomes 'gal' (I've seen this before).
'cut top off' means to remove the first letter.
'plant' with its first letter taken away is 'lant'.
'gal'+'lant'='GALLANT'
(Other definitions for gallant that I've seen before include "Charmingly attentive to ladies" , "Brave and honourable" , "Daring" , "lover" , "Amorous" .)