Pattern of behaviour regarding booze will absorb the writer (7)
I believe the answer is:
regimen
'pattern of behaviour' is the definition.
The answer and definition can be both related to thinking as well as being singular nouns.
Perhaps they are linked in a way I don't understand?
'regarding booze will absorb the writer' is the wordplay.
'regarding' becomes 're' ('re' means regarding or about).
'booze' becomes 'gin' (gin is a kind of booze).
'will absorb' is an insertion indicator.
'the writer' becomes 'me' (the person who wrote the clues).
'gin' placed around 'me' is 'gimen'.
're'+'gimen'='REGIMEN'
Can you help me to learn more?
(Other definitions for regimen that I've seen before include "Therapeutic programme (of diet and exercise)" , "Systematic course of treatment, diet, etc" , "Disciplined system" , "discipline" , "System of diet etc" .)