Ineffectual exhortation to be more economical (7)
I believe the answer is:
useless
'ineffectual' is the definition.
(similar in meaning)
I can't explain the remainder of the clue.
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" .)