Glenda is upset by relations (8)
I believe the answer is:
dealings
'relations' is the definition.
(synonyms)
'glenda is upset' is the wordplay.
'upset' indicates an anagram.
'glenda'+'is'='glendais'
'glendais' is an anagram of 'DEALINGS'.
'by' is the link.
(Other definitions for dealings that I've seen before include "cards undergo them, you might say" , "Truck" , "Traffic" , "Business transactions as in stocks and shares" .)