Ineffectual exhortation to be more economical? (7)
I believe the answer is:
useless
'ineffectual' is the definition.
(similar in meaning)
I don't understand how the remainder of the clue works.
Can you help me to learn more?
(Other definitions for useless that I've seen before include "to no avail" , "Good for nothing" , "idle" , "nohoper?" , "Serving no practical purpose" .)