Intricate bin liner stuffed with hay holds tonnes (12)
I believe the answer is:
labyrinthine
'intricate' is the definition.
(synonyms)
'bin liner stuffed with hay holds tonnes' is the wordplay.
'stuffed with' indicates an anagram.
'holds' means one lot of letters goes inside another.
'tonnes' becomes 't' (abbreviation).
'bin'+'liner'='binliner'
'binliner' anagrammed with 'hay' gives 'labyrinhine'.
'labyrinhine' enclosing 't' is 'LABYRINTHINE'.
(Other definitions for labyrinthine that I've seen before include "windy!" , "difficult to get out of" , "Like a maze" , "complex" .)