Blocks the Spanish girl (6)
I believe the answer is:
damsel
'girl' is the definition.
(damsel is a kind of girl)
'blocks the spanish' is the wordplay.
'blocks' becomes 'dams' (damming is a kind of blocking).
'the spanish' becomes 'el' ('the' in Spanish).
'dams'+'el'='DAMSEL'
(Other definitions for damsel that I've seen before include "Young lady of old, perhaps in distress" , "Young single woman" , "Medals (anag.)" , "Maid" , "Girl (literary)" .)