Inhale herb tea mistakenly (7)
I believe the answer is:
breathe
'inhale' is the definition.
(to inhale is to breathe in)
'herb tea mistakenly' is the wordplay.
'mistakenly' indicates anagramming the letters.
'herb'+'tea'='herbtea'
'herbtea' is an anagram of 'BREATHE'.
(Other definitions for breathe that I've seen before include "Draw air into, and expel out of, the lungs" , "Do this before you go under" , "live" , "Tell" , "wheeze" .)