With passion, they lead astray (8)
I believe the answer is:
heatedly
'with passion' is the definition.
(I've seen this before)
'they lead astray' is the wordplay.
'astray' indicates anagramming the letters.
'they'+'lead'='theylead'
'theylead' is an anagram of 'HEATEDLY'.
(Other definitions for heatedly that I've seen before include "With passion" , "Angrily, being warm?" , "In an emotional and inflamed manner" , "How people might argue" .)