Grunt about one with no top on being inflamed (7)
I believe the answer is:
ignited
'being inflamed' is the definition.
(thesaurus)
'grunt about one with no top on' is the wordplay.
'grunt about' becomes 'ig' (I am not sure about this - if you are sure you should believe this answer much more).
'one' becomes 'united' (similar in meaning).
'with no top on' means to remove the first letter (the first or top letter is removed).
'united' with its first letter removed is 'nited'.
'ig'+'nited'='IGNITED'
Can you help me to learn more?
(Other definitions for ignited that I've seen before include "Set on fire" , "Kindled" , "Lit" , "Caught fire" , "Sparked off" .)