Endlessly intoned, rambling in wooden tongue (5)
I believe the answer is:
tenon
'wooden tongue' is the definition.
(tongue can mean a wooden tenon joint)
'endlessly intoned rambling' is the wordplay.
'endlessly' indicates the central letters (the ends of the words are removed).
'rambling' indicates anagramming the letters.
The central letters of 'intoned' are 'ntone'.
'ntone' with letters rearranged gives 'TENON'.
'in' acts as a link.
(Other definitions for tenon that I've seen before include "Join" , "Piece of wood fitting into a mortice" , "One projecting" , "Piece of wood that fits into a mortise" , "Joint - tonne (anag)" .)