Pole only ruined material (5)
I believe the answer is:
nylon
'material' is the definition.
(nylon is a kind of material)
'pole only ruined' is the wordplay.
'pole' becomes 'n' (abbreviation for North, as in North Pole).
'ruined' indicates an anagram.
'only' with letters rearranged gives 'ylon'.
'n'+'ylon'='NYLON'
(Other definitions for nylon that I've seen before include "Cover for leg" , "Type of material" , "Hosiery material" , "Artificial fabric" , "Tough synthetic material" .)