Futile to cut back (7)
I believe the answer is:
useless
'futile' is the definition.
(similar in meaning)
I don't understand how the rest of the clue works.
Can you help me to learn more?
(Other definitions for useless that I've seen before include "Fruitless" , "Of no benefit" , "Unemployable" , "Good-for-nothing" , "Lacking in purpose" .)