Rush to ruin? Not I! (3)
I believe the answer is:
run
'rush' is the definition.
(thesaurus)
'ruin? not i' is the wordplay.
'not' indicates named letters should be taken away.
'ruin' with 'i' removed is 'RUN'.
'to' acts as a link.
(Other definitions for run that I've seen before include "Dash" , "Organise - series" , "A single" , "Scarper" , "Cricket score; go" .)