Cambridge University inflexible about withdrawing advert at intervals (7)
I believe the answer is:
harvard
'cambridge university' is the definition.
(I've seen this before)
'inflexible about withdrawing advert at intervals' is the wordplay.
'inflexible' becomes 'hard' (I can't explain this - if you can you should believe this answer much more).
'about' indicates putting letters inside.
'withdrawing' shows that the letters should be reversed in order.
'at intervals' means one should take alternating letters (letters are taken at regular intervals).
The alternate letters of 'advert' are 'avr'.
'avr' back-to-front is 'rva'.
'hard' placed around 'rva' is 'HARVARD'.
Can you help me to learn more?
(Other definitions for harvard that I've seen before include "Member of the 11 at Cambridge, Massachusetts" , "US Ivy League university" , "Ivy league university in Cambridge, Massachusetts" , "place of learning" , "US university, founded 1636" .)