Watch and he’ll do it again (8)
I believe the answer is:
repeater
'watch' is the definition.
(thesaurus)
'he'll do it again' is the wordplay.
I cannot quite understand how this works, but
'it' could be 't' (abbreviation. e.g. in 'tis) and 't' is located in the answer.
'again' could be 're' and 're' is located in the answer.
This explanation may well be incorrect...
'and' is the link.
Can you help me to learn more?
(Other definitions for repeater that I've seen before include "Amplifier in phone line" , "one feeding a duplicator" , "Burp" , "One keeps saying" , "Maybe watch" .)