Recap = summarize - reap (harvest) containing (including) c (source/first letter of corn).

You summed that one up nicely, Lex!

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Thank you!

Was unaccustomed to endless student roistering (6) - one e

Quite tricky this, or at least it kept us guessing for a while. As a first day hint: it is somewhat old fashioned usage and there is an apostrophe involved.

Was working on swager : swa = was (unaccustomed)
and swager = roistering...
So thanks for the clue; I can throw that away now!

I don't have much of a chance it it's old English
(have problems with new English!) but:
was unaccustomed = direct = untes'd
anagram of studen(t)

In case untes'd is old English for untested...

24 hours later I used Google and found 'usedn't', which is student less 't' anagrammed (roistering) = usedn't

Well done young sir! Don't get too used to wearing this:
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yez bo l'young sir...

Me young? Merci Lex.

A fab flea is genial when erratic(7)

affable (anag.)

All yours mxm. ===[**WCF**]===

Thanks Curly

Beer cans beginning to bother expert (4)

a(b)le

expert = able
beer = ale
cans = container indicator
beginning to bother = b

All yours... ===[**WCF**]===