Silly if it's not decimalised? (9)
I believe the answer is:
'silly' is the definition.
(I've seen this before)
'it's not decimalised?' is the wordplay.
I cannot really see how this works, but
'it's' could be 'es' ('e' can mean 'electronic' which is similar to 'IT') and 'es' is present in the answer.
'not' could be 'nt' (synonyms) and 'nt' is present in the answer.
This may be the basis of the clue (or it may be nonsense).
'if' acts as a link.
Can you help me to learn more?
(Other definitions for pointless that I've seen before include "missing a target" , "Quite vain" , "Futile - TV quiz show" , "Ineffectual" , "Having no bits of news" .)