Take stand over containing one leader on the other side (8)
I believe the answer is:
opposite
'other side' is the definition.
(I've seen this before)
'take stand over containing one leader on the' is the wordplay.
'take stand over' becomes 'oppose' (I can't explain this - if you can you should give a lot more credence to this answer).
'containing' means one lot of letters goes inside another.
'one' becomes 'I' (Roman numeral).
'leader on' suggests taking the first letters (the letter which leads the word).
The first letter of 'the' is 't'.
'i'+'t'='it'
'oppose' enclosing 'it' is 'OPPOSITE'.
Can you help me to learn more?
(Other definitions for opposite that I've seen before include "Adverse" , "Face to face or directly contrary" , "Contrary or face-to-face" , "Rival" , "Facing - reverse" .)