Duck takes sheep outside for wander (4)
I believe the answer is:
roam
'for wander' is the definition.
(synonyms)
'duck takes sheep' is the wordplay.
'duck' becomes 'o' (resembles zero - 'duck' in cricket).
'takes' means one lot of letters goes inside another (take can mean to capture or invade).
'sheep' becomes 'ram' (male sheep).
'o' going within 'ram' is 'ROAM'.
'outside' is the link.
This may not be correct. It may be part of another bit of the clue.
Can you help me to learn more?
(Other definitions for roam that I've seen before include "Ramble without purpose" , "Stray" , "Walk without a specific destination" , "wander around" , "Wander widely" .)