Supporters only upset amid pointless extremes (6)
I believe the answer is:
pylons
'supporters' is the definition.
Although both the answer and definition are plural nouns, I can't see how they can define each other.
'only upset amid pointless extremes' is the wordplay.
'upset' is an anagram indicator.
'amid' is an insertion indicator.
'extremes' suggests removing the centre.
'pointless' with its middle removed is 'ps'.
'only' is an anagram of 'ylon'.
'ylon' placed inside 'ps' is 'PYLONS'.
Can you help me to learn more?
(Other definitions for pylons that I've seen before include "Structures for high-tension wires" , "Steel towers supporting high-tension wires" , "Electricity cable supports" , "Large vertical steel towers" .)