Type of fever giving gran a dull disorder (9)
I believe the answer is:
glandular
'type of fever' is the definition.
(I've seen this before)
'gran a dull disorder' is the wordplay.
'disorder' indicates an anagram (a disordered version of the letters).
'gran'+'a'+'dull'='granadull'
'granadull' is an anagram of 'GLANDULAR'.
'giving' acts as a link.
(Other definitions for glandular that I've seen before include "Kind of fever" , "Type of fever" , "regarding body parts" , "Sort of fever" .)