Reportedly thin fleece (5)
I believe the answer is:
shear
'fleece' is the definition.
('shear' can be a synonym of 'fleece')
'reportedly thin' is the wordplay.
'reportedly' shows a homophone (sound like).
'thin' becomes 'sheer' ('sheer' can be similar in meaning to 'thin').
'sheer' is a homophone of 'SHEAR'.
(Other definitions for shear that I've seen before include "Remove sheep's wool" , "shave" , "Remove a fleece" , "Fleece (a sheep)" , "Cut the wool of 14 across" .)