No good if it’s in need of sharpening (9)
I believe the answer is:
pointless
'no good' is the definition.
Both the definition and answer are adjectives. Maybe there's an association between them I don't understand?
'it's in need of sharpening' is the wordplay.
I cannot quite see how this works, but
'it's' could be 'es' ('e' can mean 'electronic' which is similar to 'IT') and 'es' is found in the answer.
'in' is found in the answer.
'of' could be 'o' and 'o' is found in the answer.
This explanation may well be incorrect...
'if' is the link.
Can you help me to learn more?
(Other definitions for pointless that I've seen before include "no avail" , "Futile - blunt" , "Futile - TV quiz show" , "Ineffectual" , "unprofitable" .)