A duck and a sheep out to go astray (4)
I believe the answer is:
roam
'go astray' is the definition.
'roam' can be an answer for 'go' (roaming is a kind of going). I am not sure about the 'astray' bit.
'a duck and a sheep out' is the wordplay.
'a duck' becomes 'o' (resembles zero - 'duck' in cricket).
'and' means one lot of letters go next to another.
'sheep' becomes 'rm' (I can't justify this - if you can you should give a lot more credence to this answer).
'out' is an insertion indicator.
'o'+'a'='oa'
'oa' put inside 'rm' is 'ROAM'.
'to' is the link.
Can you help me to learn more?
(Other definitions for roam that I've seen before include "Ramble without purpose" , "Wander freely" , "Move about aimlessly" , "Wander about aimlessly" , "Prowl" .)