What bacilli regularly can make you (3)
I believe the answer is:
ail
'what bacilli' is the definition.
I can't judge whether this defines the answer.
'regularly can make you' is the wordplay.
'regularly' means one should take alternating letters (regularly take one letter, leave next etc.).
'make you' becomes 'il' (I can't justify this - if you can you should give a lot more credence to this answer).
The alternating letters of 'can' are 'a'.
'a'+'il'='AIL'
Can you help me to learn more?
(Other definitions for ail that I've seen before include "Become sick" , "Afflict -- feel unwell" , "Be the worse for wear" , "Be unwell, feel poorly" , "Go sick" .)