That strange London lecturer must leave after cool event (10)
I believe the answer is:
heptathlon
'event' is the definition.
(I've seen this before)
'that strange london lecturer must leave after cool' is the wordplay.
'strange' indicates anagramming the letters.
'lecturer' becomes 'don' (don can mean an academic).
'must leave' is a deletion indicator.
'after' means one lot of letters go next to another.
'cool' becomes 'hep' (I've seen this in another clue).
'london' with 'don' taken out is 'lon'.
'that' with letters rearranged gives 'tath'.
'tath'+'lon'='tathlon'
'tathlon' after 'hep' is 'HEPTATHLON'.
(Another definition for heptathlon that I've seen is " event".)