Avoid the Spanish union leader, extremely disreputable (5)
I believe the answer is:
elude
'avoid' is the definition.
(I know that elude is a more specific form of avoid)
'the spanish union leader extremely disreputable' is the wordplay.
'the spanish' becomes 'el' ('the' in Spanish).
'leader' suggests taking the first letters.
'extremely' means to remove the middle letters (only the extremes of the word are used).
'disreputable' with its middle removed is 'de'.
The first letter of 'union' is 'u'.
'el'+'u'+'de'='ELUDE'
(Other definitions for elude that I've seen before include "Escape by stratagem" , "Puzzle" , "Evade; baffle" , "Escape - avoid" , "Evade, escape from" .)