To sum up, offers blow over ecstasy at college (5)
I believe the answer is:
Here is my best explanation:
'to sum up' is the definition.
(recapping is a kind of summing up)
'blow over ecstasy at college' is the subsidiary indication.
'blow' becomes 'rap' (rap is a kind of blow**).
'over' is an insertion indicator.
'ecstasy' becomes 'e' (common term for the illegal drug).
'at' is a charade indicator (letters next to each other).
'college' becomes 'c'.
'rap' enclosing 'ec' is 'recap'.
'offers' is the link.
(Other definitions for recap that I've seen before include "Summarising statement", "sum everything up", "Summarise at the end", "Summary of main points", "In brief, say it again", "cover the same ground again", "Sum up (abbrev.)", "Go over again in the mind", "Go back over the main points" and "Run through again (Inf)".)