Points along the line (4)
I believe the answer is:
dots
'points' is the definition.
('dot' can be a synonym of 'point')
'along the line' is the wordplay.
'along' becomes 'dos' (I can't explain this - if you can you should give a lot more credence to this answer).
'the' becomes 't' (the is pronounced as a 't' sound in some dialects).
'line' indicates putting letters inside.
'dos' going around 't' is 'DOTS'.
Can you help me to learn more?
(Other definitions for dots that I've seen before include "Very small round shapes" , "Short signals in Morse cods" , "Tiny spots" , "Tiny circles" , "Tiny circular shapes" .)