Essential wear first and foremost for Shrek character (6)
I believe the answer is:
'foremost for shrek character' is the definition.
I can't judge whether this definition defines the answer.
'essential wear first' is the wordplay.
'essential' becomes 'key' (key can mean essential or important).
'wear' becomes 'don' (to don an item of clothing is to wear it).
'first' means one lot of letters go next to another.
'key' after 'don' is 'DONKEY'.
'and' acts as a link.
Can you help me to learn more?
(Other definitions for donkey that I've seen before include "Fool" , "Domesticated ass" , "This work is drudgery - by long-eared animal?" , "'Little --', Christmas song" , "Nativity play animal?" .)