Tense, buttonholed by more brusque male, but not for long (5-4)
I believe the answer is:
short-term
'not for long' is the definition.
I can't tell whether this defines the answer.
'tense buttonholed by more brusque male' is the wordplay.
'tense' becomes 't' (grammatical abbreviation).
'buttonholed by' means one lot of letters goes inside another (buttonhole can mean to detain or hold).
'more brusque' becomes 'shorter' ('short' can be a synonym of 'brusque').
'male' becomes 'm' (common abbreviation).
't' inserted into 'shorter' is 'shortter'.
'shortter'+'m'='SHORT-TERM'
'but' is the link.
Can you help me to learn more?
(Other definitions for short-term that I've seen before include "Concerned with the near future" , "Not concerned with long timescales" , "Not lasting long" , "Not long-lasting" , "Temporary" .)