Go astray and possibly end in big trouble (6)
I believe the answer is:
wander
'go astray' is the definition.
(I've seen this before)
'possibly end in big trouble' is the wordplay.
'possibly' is an anagram indicator.
'in' is an insertion indicator.
'big trouble' becomes 'war' (I am not sure about this - if you are sure you should give a lot more credence to this answer).
'end' anagrammed gives 'nde'.
'nde' inserted into 'war' is 'WANDER'.
'and' acts as a link.
Can you help me to learn more?
(Other definitions for wander that I've seen before include "Move about aimlessly" , "Travel aimlessly" , "Warden (anag.)" , "Go astray" , "Roam about or digress" .)