Glandular ailment causes a bit of hesitation in the chemist (5)
I believe the answer is:
mumps
'glandular ailment' is the definition.
The answer and definition can be both states of affairs as well as being singular nouns.
Maybe they are linked in a way I don't understand?
'bit of hesitation in the chemist' is the wordplay.
'bit of hesitation' becomes 'um' (expression of hesitation).
'in the' indicates putting letters inside.
'chemist' becomes 'mps' (I can't justify this - if you can you should believe this answer much more).
'um' put within 'mps' is 'MUMPS'.
'causes a' is the link.
Can you help me to learn more?
(Other definitions for mumps that I've seen before include "Contagious viral disease" , "Complaint" , "Swelling disease" , "Acute viral disease, often in children" , "Gland-swelling disease" .)