Surrounded by a certain amount of humidity (3)
I believe the answer is:
mid
'surrounded by a certain amount' is the definition.
I can't tell whether this defines the answer.
'of humidity' is the wordplay.
'of' indicates a hidden word.
'MID' is hidden within 'humidity'.
Can you help me to learn more?
(Other definitions for mid that I've seen before include "Of the central part" , "Dim sort of prefix" , "Denote the centre point" , "Prefix meaning centre" .)