Call to engage team working in undesirable post (4,4)
I believe the answer is:
hate mail
'post' is the definition.
(I know that hate mail is a type of post)
'call to engage team working' is the wordplay.
'call' becomes 'hail' (hailing is a kind of calling).
'to engage' means one lot of letters goes inside another (some letters get engaged in others).
'working' indicates an anagram.
'team' with letters rearranged gives 'atem'.
'hail' going around 'atem' is 'HATE MAIL'.
'in undesirable' is the link.
I am not very happy about this link. Some or all of it may be part of another bit of the clue.
Can you help me to learn more?
(Other definitions for hate mail that I've seen before include "Abusive letter that expresses loathing" , "Offensive correspondence" , "Poison-pen letters" , "Poison pen letters" , "Hostile message" .)