The Spanish suited strange lethargy (9)
I believe the answer is:
lassitude
'lethargy' is the definition.
(I know that lethargy can be written as lassitude)
'the spanish suited strange' is the wordplay.
'the spanish' becomes 'las' ('the' in Spanish).
'strange' is an anagram indicator.
'suited' anagrammed gives 'situde'.
'las'+'situde'='LASSITUDE'
(Other definitions for lassitude that I've seen before include "Listlessness, state of apathy" , "Listlessness, lethargy" , "Listlessness, fatigue" , "Is saluted with tiredness" , "slackness" .)