Pam's not going around with Pat (7)
I believe the answer is:
postman
'pat' is the definition.
Although both the answer and definition are singular nouns, I cannot see how they can define each other.
'pam's not going around' is the wordplay.
'going around' indicates anagramming the letters.
'pams'+'not'='pamsnot'
'pamsnot' anagrammed gives 'POSTMAN'.
'with' acts as a link.
Can you help me to learn more?
(Other definitions for postman that I've seen before include "Chap with letters" , "Mail deliverer" , "one delivers" , "Letter deliverer" , "Male mail carrier" .)