Start seeing changes close to Brussels (7)
I believe the answer is:
genesis
'start' is the definition.
(I've seen this before)
'seeing changes close to brussels' is the wordplay.
'changes' indicates an anagram.
'close to' suggests the final letters (the 'close' to the word).
The final letter of 'brussels' is 's'.
'seeing' is an anagram of 'genesi'.
'genesi'+'s'='GENESIS'
(Other definitions for genesis that I've seen before include "Creation" , "Origin or formation of something" , "name of group" , "the start of something" , "First book of the Old Testament" .)