A go-ahead thing to do (3,2)
I believe the answer is:
get on
'do' is the definition.
(thesaurus)
'a go-ahead thing' is the wordplay.
I cannot really see how this works, but
'go' could be 'get' (synonyms) and 'get' is located in the answer.
'ahead' could be 'on' (synonyms) and 'on' is located in the answer.
No letters remain.
This may be the basis of the clue (or it may be nonsense).
'to' is the link.
Can you help me to learn more?
(Other definitions for get on that I've seen before include "Make progress or climb aboard" , "Board vehicle or make progress" , "Hit it off" , "Enjoy harmonious relationship" , "Advance; prosper" .)