Banked on the Spanish being in dire trouble (6)
I believe the answer is:
relied
'banked' is the definition.
(I've seen this before)
'the spanish being in dire trouble' is the wordplay.
'the spanish' becomes 'el'.
'being in' is an insertion indicator.
'trouble' is an anagram indicator.
'dire' anagrammed gives 'ried'.
'el' going inside 'ried' is 'RELIED'.
'on' acts as a link.
(Other definitions for relied that I've seen before include "Trusted confidently, depended on" , "Was dependent (on)" , "Had confidence" , "Banked" , "Assembled as before" .)