Sweating from exercises arranged in airports (12)
I believe the answer is:
perspiration
'sweating' is the definition.
(thesaurus)
'exercises arranged in airports' is the wordplay.
'exercises' becomes 'pe' (Physical Education class).
'arranged' indicates anagramming the letters.
'in'+'airports'='inairports'
'inairports' with letters rearranged gives 'rspiration'.
'pe'+'rspiration'='PERSPIRATION'
'from' acts as a link.
(Other definitions for perspiration that I've seen before include "is exuded" , "Ninety nine percent of genius" , "Sweat" .)