Put it on air and it ruined the generator (9)
I believe the answer is:
initiator
'generator' is the definition.
(thesaurus)
'put it on air and it ruined' is the wordplay.
'put' means one lot of letters goes inside another.
'and' says to put letters next to each other.
'ruined' is an anagram indicator.
'on'+'air'+'it'='onairit'
'onairit' with letters rearranged gives 'iniator'.
'it' put inside 'iniator' is 'INITIATOR'.
'the' is the link.
(Other definitions for initiator that I've seen before include "One starting (a process)" , "Substance starting a chain reaction" , "beginner" , "One starts" , "originator" .)