Second attempt to go round university, large, when it's hot and humid (6)
I believe the answer is:
sultry
'it's hot and humid' is the definition.
(I've seen this in another clue)
'second attempt to go round university large' is the wordplay.
'second' becomes 's' (common abbreviation).
'attempt to' becomes 'try' (I've seen this in other clues).
'go round' says to put letters next to each other.
'university' becomes 'U' (abbreviation as in UMass).
'large' becomes 'L' (eg in clothes sizes).
'u'+'l'='ul'
'try' put after 'ul' is 'ultry'.
's'+'ultry'='SULTRY'
'when' acts as a link.
(Other definitions for sultry that I've seen before include "Close -- sensual" , "(Of weather) hot, humid" , "Sweltering, close and oppressive" , "Hot, close (weather)" , "Passionate" .)