An eccentric revolutionary, that Spanish primate (7)
I believe the answer is:
macaque
'primate' is the definition.
(I know that macaque is a type of Old World monkey)
'an eccentric revolutionary that spanish' is the wordplay.
'an' becomes 'a'.
'eccentric' becomes 'cam' (an eccentric is a mechanical device such as a cam).
'revolutionary' is a reversal indicator.
'that spanish' becomes 'que' ('that' in Spanish).
'a'+'cam'='acam'
'acam' back-to-front is 'maca'.
'maca'+'que'='MACAQUE'
(Other definitions for macaque that I've seen before include "Barbary ape" , "mammal" , "Long-faced monkey" , "Monkey with a short or no tail" , "Long-tailed monkey" .)