Starting studying inside; had to go back to punctuation (4)
I believe the answer is:
dash
'punctuation' is the definition.
(dash is a kind of punctuation)
'starting studying inside had to go back' is the wordplay.
'starting' says to take the initial letters.
'inside' indicates putting letters inside.
'to go back' says the letters should be written backwards.
The initial letter of 'studying' is 's'.
's' placed into 'had' is 'hsad'.
'hsad' backwards is 'DASH'.
'to' acts as a link.
(Other definitions for dash that I've seen before include "Drop" , "Daring" , "Hurl; rush" , "Morse feature" , "Short line; run" .)