Spanish couple gets terribly subtle, very probably (9)
I believe the answer is:
doubtless
'very probably' is the definition.
(I've seen this before)
'spanish couple gets terribly subtle' is the wordplay.
'spanish couple' becomes 'dos-' ('two' in Spanish).
'gets' means one lot of letters goes inside another (gets can mean captures or absorbs).
'terribly' indicates an anagram.
'subtle' with letters rearranged gives 'ubtles'.
'dos' placed around 'ubtles' is 'DOUBTLESS'.
(Other definitions for doubtless that I've seen before include "Unquestionably" , "Probably, certainly" , "Assuredly" , "of course" , "Positive" .)