Shepherd's first try to remove a fleece (5)
I believe the answer is:
shear
'remove a fleece' is the definition.
(I've seen this before)
'shepherd's first try' is the wordplay.
'shepherd's first' becomes 's' (1st letter of 'shepherd').
'try' becomes 'hear' (as in to try someone in court or hear their case).
's'+'hear'='SHEAR'
'to' acts as a link.
(Other definitions for shear that I've seen before include "Remove sheep's wool" , "shave" , "Cut sheep's woll with large scissors" , "Fleece; cut" , "Remove a fleece" .)