Babbling when in company with her ardent followers (10)
I believe the answer is:
incoherent
'babbling' is the definition.
(I've seen this in another clue)
'in company with her ardent followers' is the wordplay.
'company' becomes 'co' (abbreviation).
'with' says to put letters next to each other.
'ardent followers' becomes 'ent' (I can't justify this - if you can you should give a lot more credence to this answer).
'in'+'co'+'her'+'ent'='INCOHERENT'
'when' is the link.
Can you help me to learn more?
(Other definitions for incoherent that I've seen before include "Internally inconsistent" , "difficult to understand" , "rambling" , "drunk?" , "Confused" .)