The Spanish bend part of arm (5)
I believe the answer is:
elbow
'part of arm' is the definition.
('elbow' is part of 'arm')
'the spanish bend' is the wordplay.
'the spanish' becomes 'el' ('the' in Spanish).
'bend' becomes 'bow' (bowing is a kind of bending).
'el'+'bow'='ELBOW'
(Other definitions for elbow that I've seen before include "Sort of grease" , "Hinged joint" , "sack?" , "Sharp bend in a road or river" , "Below (anag.)" .)