What does the cryptic crossword clue "Engineer to shake up new lot being dim-witted (4,2,3,6)" mean?

The definition is "being dim-witted". The wordplay uses an anagram. anagram of TO SHAKE UP NEW LOT = SLOWONTHEUPTAKE The answer is SLOWONTHEUPTAKE.

Engineer to shake up new lot being dim-witted (4,2,3,6)

Guardian Cryptic #29546 | 1 Down | 2024-11-21 flower