Fungal problem has doctor turning blue (3,3)
I believe the answer is:
dry rot
'fungal problem' is the definition.
'dry rot' can be an answer for 'problem' (I have seen 'domestic problem' mean 'dry rot' so perhaps 'problem' could also mean 'dry rot'). I am not sure about the 'fungal' bit.
'doctor turning blue' is the wordplay.
'doctor' becomes 'dr' (abbreviation).
'turning' says the letters should be written in reverse.
'blue' becomes 'tory' (I've seen this in other clues).
'tory' reversed gives 'yrot'.
'dr'+'yrot'='DRY-ROT'
'has' is the link.
Can you help me to learn more?
(Other definitions for dry rot that I've seen before include "infestation" , "Usual, customary" , "Decay of wood not well ventilated" , "Decay of timber caused by fungus" , "Decay of wood poorly ventilated" .)