Place too great a burden on (8)
I believe the answer is:
overload
'place too great a burden on' is the definition.
(I've seen this before)
This is the entire clue.
(Other definitions for overload that I've seen before include "Excessive electrical demand" , "Place too great a burden on" , "saddle" , "Put too great a demand on (electric circuit)" , "Weigh down" .)