Mrs Doyen strangely has a pattern of symptoms (8)
I believe the answer is:
syndrome
'a pattern of symptoms' is the definition.
(I've seen this in another clue)
'mrs doyen strangely' is the wordplay.
'strangely' is an anagram indicator.
'mrs'+'doyen'='mrsdoyen'
'mrsdoyen' with letters rearranged gives 'SYNDROME'.
'has' acts as a link.
(Other definitions for syndrome that I've seen before include "Set of linked symptoms" , "Characteristic group of symptoms" , "Set of symptoms indicating disease" , "set of opinions" , "Signs of disorder" .)