I expect complaint: university with old teacher's regressing (2,5)
I believe the answer is:
no doubt
'i expect' is the definition.
I can't judge whether this defines the answer.
'complaint university with old teacher's regressing' is the wordplay.
'complaint' becomes 'TB' (short for tuberculosis).
'university' becomes 'u' (abbreviation for university).
'with old' becomes 'o' (common abbreviation eg in OE for Old English. I am not sure about the 'with' bit.).
'teacher' becomes 'don' (don is a kind of teacher).
'regressing' shows that the letters should be reversed in order (to regress is to go backwards).
'tb'+'u'+'o'+'don'='tbuodon'
'tbuodon' written backwards gives 'NO DOUBT'.
Can you help me to learn more?
(Other definitions for no doubt that I've seen before include "To be sure" , "Almost certainly" , "Surely" , "sign of agreement" , "Bound to, unquestionably" .)