Endlessly intertwine garland (6)
I believe the answer is:
wreath
'garland' is the definition.
(I know that garland can be written as wreath)
'endlessly intertwine' is the wordplay.
'endlessly' means to remove the last letter.
'intertwine' becomes 'wreathe' (wreathing is a kind of intertwining).
'wreathe' with its final letter taken off is 'WREATH'.
(Other definitions for wreath that I've seen before include "Flower arrangement" , "Circle of flowers in honour of dead" , "Flower circle for grave" , "Circlet (of laurel)" , "A ring of leaves and flowers" .)