Forgets in the end to go to shopping centre to get drink but it's not important (9)
I believe the answer is:
smallbeer
'it's not important' is the definition.
I can't tell whether this defines the answer.
'forgets in the end to go to shopping centre to get drink' is the wordplay.
'in the end' suggests the final letters.
'to go to' is a charade indicator (letters next to each other).
'shopping centre' becomes 'mall' (a mall is a large shopping complex).
'to get' means one lot of letters go next to another.
'drink' becomes 'beer' (beer is a kind of drink).
The last letter of 'forgets' is 's'.
's'+'mall'+'beer'='SMALLBEER'
'but' is the link.
Can you help me to learn more?
(Other definitions for smallbeer that I've seen before include "A half pint, say" , "something of no importance" .)