Put out fire -- enter block (9)
I believe the answer is:
interfere
'block' is the definition.
(thesaurus)
'put out fire enter' is the wordplay.
'put out' indicates an anagram.
'fire'+'enter'='fireenter'
'fireenter' with letters rearranged gives 'INTERFERE'.
(Other definitions for interfere that I've seen before include "Meddle in someone else's business" , "Come between, intervene" , "Obstruct, pry" , "Meddle, intrude" , "Poke one's nose in" .)