Take advantage of endless ribbon (3)
I believe the answer is:
tap
'take advantage' is the definition.
(I've seen this before)
'endless ribbon' is the wordplay.
'endless' means to remove the last letter.
'ribbon' becomes 'tape' (I've seen this before).
'tape' with its final letter taken off is 'TAP'.
'of' acts as a link.
(Other definitions for tap that I've seen before include "Bugging device" , "Make use of; water from it" , "Sort of dance" , "Water controller" , "Light blow; draw sap from (tree)" .)