Almost on time, three sides add stops, etc. (9)
I believe the answer is:
punctuate
'add stops etc' is the definition.
I can't judge whether this definition defines the answer.
'almost on time three sides' is the wordplay.
'almost' means to remove the last letter (most of the word but not all of it).
'on time' becomes 'punctual' (similar in meaning).
'sides' suggests removing the centre (only the letters on the sides are used).
'three' with its middle removed is 'te'.
'punctual' with its last letter taken away is 'punctua'.
'punctua'+'te'='PUNCTUATE'
Can you help me to learn more?
(Other definitions for punctuate that I've seen before include "Insert full stops, commas, etc in (text)" , "Add marks to text" , "Interrupt periodically" , "Regularly interrupt" .)