Glandular tissue helps to hide malformed node (8)
I believe the answer is:
adenoids
'glandular tissue' is the definition.
(masses of tissue within the throat)
'helps to hide malformed node' is the wordplay.
'helps' becomes 'aids' ('aid' can be a synonym of 'help').
'to hide' is an insertion indicator.
'malformed' is an anagram indicator.
'node' with letters rearranged gives 'deno'.
'aids' enclosing 'deno' is 'ADENOIDS'.
(Other definitions for adenoids that I've seen before include "Enlarged spongy tissue between back of nose and throat" , "Lymph tissue towards back of throat" , "Tissues between back o fnose and throat, sometimes hinder breathing" , "Enlarged spongy tissues between back of nose and throat" , "Glandular tissue at back of nose" .)