Curious tree was top (7)
I believe the answer is:
sweater
'top' is the definition.
(type of top or jumper)
'curious tree was' is the wordplay.
'curious' indicates anagramming the letters.
'tree'+'was'='treewas'
'treewas' with letters rearranged gives 'SWEATER'.
(Other definitions for sweater that I've seen before include "Guernsey" , "person in a sauna?" , "Re waste: it's a garment" , "slave-driver" , "Warm garment" .)