Writer's picked up van - it's broken down outside A&E? (8)
I believe the answer is:
vitamins
'writer's picked up van it's broken down outside ae?' is the definition.
I can't tell whether this defines the answer.
'writer's picked up van it's broken down outside' is the wordplay.
'writer's' becomes 'im' ('writer's' could mean 'the crossword setter is').
'picked up' is a reversal indicator.
'broken down' is an anagram indicator.
'outside' is an insertion indicator.
'im' backwards is 'mi'.
'van'+'its'='vanits'
'vanits' anagrammed gives 'vitans'.
'mi' put into 'vitans' is 'VITAMINS'.
Can you help me to learn more?
(Other definitions for vitamins that I've seen before include "Essential substances found in mini vats, oddly" , "Nutrition supplements" , "Essential substances, A, B, B6, etc" , "They're essential to normal metabolism" , "Thiamine, riboflavin, etc" .)