Take one into the outskirts of Venice (6)
I believe the answer is:
Here is my best explanation:
'take' is the definition.
(thieving is a kind of taking)
'one into the outskirts of venice' is the subsidiary indication.
'one' becomes 'i' (roman numeral).
'into' means one lot of letters goes inside another.
'outskirts of' says to hollow out the word (remove centre letters).
'venice' with its centre taken out is 've'.
'i' going inside 'the' is 'thie'.
(Other definitions for thieve that I've seen before include "Misappropriate", "Take illegally", "Steal things", "Knock off", "Rob", "Nick things", "Pinch" and "Pilfer".)