Fizzy drink delivery outside extremely shoddy base for armchair sport? (7,8)
I believe the answer is:
fantasy football
'armchair sport?' is the definition.
'fizzy drink delivery outside extremely shoddy base' is the wordplay.
'fizzy drink' becomes 'fanta' (brand of fizzy drink).
'delivery' becomes 'ball' (ball is a kind of delivery).
'outside' means one lot of letters goes inside another.
'extremely' says to hollow out the word (remove centre letters).
'base' becomes 'foot' (synonyms).
'shoddy' with its centre removed is 'sy'.
'fanta'+'ball'='fantaball'
'sy'+'foot'='syfoot'
'fantaball' going around 'syfoot' is 'FANTASY FOOTBALL'.
'for' acts as a link.
(Another definition for fantasy football that I've seen is " management game".)