Picked up sterilised tool (5)
I believe the answer is:
spade
'tool' is the definition.
(spade is a kind of tool)
'picked up sterilised' is the wordplay.
'picked up' shows a homophone (sound like).
'sterilised' becomes 'spayed' (spaying is a kind of sterilizing).
'spayed' is a homophone of 'SPADE'.
(Other definitions for spade that I've seen before include "Garden implement" , "Fictional detective" , "Gardening tool (maybe so called)" , "One in a suit" , "a gardener's needs?" .)