Brussels collecting money raised to form alliance (5)
I believe the answer is:
unite
'form alliance' is the definition.
'brussels collecting money raised' is the wordplay.
'brussels' becomes 'eu' (European Parliament is based in Brussels).
'collecting' is an insertion indicator.
'money' becomes 'tin' (I've seen this before).
'raised' shows that the letters should be reversed in order.
'eu' going around 'tin' is 'etinu'.
'etinu' backwards is 'UNITE'.
'to' is the link.
(Other definitions for unite that I've seen before include "ally" , "Join together, become one" , "Make one" , "Put together" , "Join forces" .)