You and I run, revealing fungal problem (3,3)

I believe the answer is:

wet rot

I'm a little stuck... Click here to teach me more about this clue!

'fungal problem' is the definition.
The definition suggests a singular noun which matches the answer.

'you and i run' is the wordplay.
'you and i' becomes 'we' (we means you and I).
'run' becomes 'trot' (trotting is a kind of running).
'we'+'trot'='WET ROT'

'revealing' is the link.

Can you help me to learn more?

(Other definitions for wet rot that I've seen before include "Timber fungus" , "type of decay" .)

I've seen this clue in The Independent.

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