Helping to bring in the Spanish alliance (8)
I believe the answer is:
relation
'alliance' is the definition.
(thesaurus)
'helping to bring in the spanish' is the wordplay.
'helping' becomes 'ration' (I've seen this before).
'to bring in' means one lot of letters goes inside another.
'the spanish' becomes 'el' ('the' in Spanish).
'ration' going around 'el' is 'RELATION'.
(Other definitions for relation that I've seen before include "Story; member of family" , "Person connected by blood or marriage" , "report" , "Mum or dad" , "Eg, father" .)