American University visitor leaving Spain for a month (6)
I believe the answer is:
august
'a month' is the definition.
(August is an example)
'american university visitor leaving spain' is the wordplay.
'american' becomes 'a' (common abbreviation - e.g. in organisation names).
'university' becomes 'u'.
'visitor' becomes 'guest' (guest is a kind of visitor).
'leaving' indicates named letters should be taken away.
'spain' becomes 'e' (abbreviation for Espana).
'guest' with 'e' taken out is 'gust'.
'a'+'u'+'gust'='AUGUST'
'for' is the link.
(Other definitions for august that I've seen before include "Pale-faced fool" , "Revered" , "there's not much of it left now [27 AUGUST]" , "For Edna O'Brien, it was a 27 across month" , "A grand month?" .)