Clasp loose on the Spanish knife (7)
I believe the answer is:
scalpel
'knife' is the definition.
(I know that scalpel is a type of surgical knife)
'clasp loose on the spanish' is the wordplay.
'loose' is an anagram indicator (letters are loosened from their original positions).
'on' is a charade indicator (letters next to each other).
'the spanish' becomes 'el' ('the' in Spanish).
'clasp' anagrammed gives 'scalp'.
'scalp'+'el'='SCALPEL'
(Other definitions for scalpel that I've seen before include "Surgical instrument" , "Surgeon's instrument" , "Surgical tool" , "Sharp cutting tool" , "sharp knife" .)