Fixed idea old boy expressed in boozy binge (7)
I believe the answer is:
session
'boozy binge' is the definition.
The answer and definition can be both acts as well as being singular nouns.
Perhaps they are linked in a way I don't understand?
'fixed idea old boy expressed' is the wordplay.
'fixed idea' becomes 'obsession' (I've seen this before).
'old boy' becomes 'OB' (abbreviation for a private school 'old boy').
'expressed' indicates named letters should be taken away (express can mean to squeeze out).
'obsession' with 'ob' removed is 'SESSION'.
'in' acts as a link.
Can you help me to learn more?
(Other definitions for session that I've seen before include "Period of business for official body" , "Meeting or series of meetings" , "Period devoted to an activity" , "Meeting, sitting, term" , "Fifty minutes lying on a couch" .)