Garden tool he carries round (3)
I believe the answer is:
hoe
'garden tool' is the definition.
(I've seen this in another clue)
'he carries round' is the wordplay.
'carries' means one lot of letters goes inside another (inserted letters carried inside).
'round' becomes 'o' (round can mean a round object).
'he' enclosing 'o' is 'HOE'.
(Other definitions for hoe that I've seen before include "Garden implement" , "Weeding tool" , "Romanians (anag) -- European enclave" , "Weeding implement" , "Use garden tool" .)