Borders of Paraguay disrupt serene mountain range (8)
I believe the answer is:
pyrenees
'mountain range' is the definition.
(I've seen this before)
'borders of paraguay disrupt serene' is the wordplay.
'borders of' suggests removing the centre.
'disrupt' is an anagram indicator.
'paraguay' with its centre taken out is 'py'.
'serene' is an anagram of 'renees'.
'py'+'renees'='PYRENEES'
(Other definitions for pyrenees that I've seen before include "French/Spanish mountains" , "European mountain range" , "Chain of mountains" , "European mountains" , "Mountains between France and Spain" .)