Hello, Elle.
I thought it was colder today.
4d, is new to me. I have "am-dram" "a MD (managing director) with drive/"ram".
The definition is "unrewarding roles".
I liked 17a. Suspend is "prorogue". "For"/pro with "not behaving predictably"/rogue.
16 The Christian is "Fletcher" giving "mutineer".
"largely saying nothing" is "mut(e)", "in" for "smart"? and the poetic "e'er" for "at any time".
I am not completely happy with my parse for this, but it's pretty close, I think.
20 is new to me. "Ecofin". It's a group of European finance ministers, or something like that.
"Upset charming" is "nice" reversed and hosting "of" in the clue.
"In a bad way". I see it as " I nab ad way". "Ad" is the promotion, "way" is "technique". "Poorly" is the definition.
I had a kipper for my tea!